# [Scipy-svn] r3951 - in trunk/scipy/integrate: linpack_lite odepack

scipy-svn@scip... scipy-svn@scip...
Tue Feb 19 23:39:10 CST 2008

Author: oliphant
Date: 2008-02-19 23:39:03 -0600 (Tue, 19 Feb 2008)
New Revision: 3951

trunk/scipy/integrate/linpack_lite/zgbfa.f
trunk/scipy/integrate/linpack_lite/zgbsl.f
trunk/scipy/integrate/linpack_lite/zgefa.f
trunk/scipy/integrate/linpack_lite/zgesl.f
trunk/scipy/integrate/odepack/zvode.f
Log:
Add missing pieces from ticket #334

===================================================================
--- trunk/scipy/integrate/linpack_lite/zgbfa.f	2008-02-20 05:27:16 UTC (rev 3950)
+++ trunk/scipy/integrate/linpack_lite/zgbfa.f	2008-02-20 05:39:03 UTC (rev 3951)
@@ -0,0 +1,181 @@
+      subroutine zgbfa(abd,lda,n,ml,mu,ipvt,info)
+      integer lda,n,ml,mu,ipvt(1),info
+      complex*16 abd(lda,1)
+c
+c     zgbfa factors a complex*16 band matrix by elimination.
+c
+c     zgbfa is usually called by zgbco, but it can be called
+c     directly with a saving in time if  rcond  is not needed.
+c
+c     on entry
+c
+c        abd     complex*16(lda, n)
+c                contains the matrix in band storage.  the columns
+c                of the matrix are stored in the columns of  abd  and
+c                the diagonals of the matrix are stored in rows
+c                ml+1 through 2*ml+mu+1 of  abd .
+c                see the comments below for details.
+c
+c        lda     integer
+c                the leading dimension of the array  abd .
+c                lda must be .ge. 2*ml + mu + 1 .
+c
+c        n       integer
+c                the order of the original matrix.
+c
+c        ml      integer
+c                number of diagonals below the main diagonal.
+c                0 .le. ml .lt. n .
+c
+c        mu      integer
+c                number of diagonals above the main diagonal.
+c                0 .le. mu .lt. n .
+c                more efficient if  ml .le. mu .
+c     on return
+c
+c        abd     an upper triangular matrix in band storage and
+c                the multipliers which were used to obtain it.
+c                the factorization can be written  a = l*u  where
+c                l  is a product of permutation and unit lower
+c                triangular matrices and  u  is upper triangular.
+c
+c        ipvt    integer(n)
+c                an integer vector of pivot indices.
+c
+c        info    integer
+c                = 0  normal value.
+c                = k  if  u(k,k) .eq. 0.0 .  this is not an error
+c                     condition for this subroutine, but it does
+c                     indicate that zgbsl will divide by zero if
+c                     called.  use  rcond  in zgbco for a reliable
+c                     indication of singularity.
+c
+c     band storage
+c
+c           if  a  is a band matrix, the following program segment
+c           will set up the input.
+c
+c                   ml = (band width below the diagonal)
+c                   mu = (band width above the diagonal)
+c                   m = ml + mu + 1
+c                   do 20 j = 1, n
+c                      i1 = max0(1, j-mu)
+c                      i2 = min0(n, j+ml)
+c                      do 10 i = i1, i2
+c                         k = i - j + m
+c                         abd(k,j) = a(i,j)
+c                10    continue
+c                20 continue
+c
+c           this uses rows  ml+1  through  2*ml+mu+1  of  abd .
+c           in addition, the first  ml  rows in  abd  are used for
+c           elements generated during the triangularization.
+c           the total number of rows needed in  abd  is  2*ml+mu+1 .
+c           the  ml+mu by ml+mu  upper left triangle and the
+c           ml by ml  lower right triangle are not referenced.
+c
+c     linpack. this version dated 08/14/78 .
+c     cleve moler, university of new mexico, argonne national lab.
+c
+c     subroutines and functions
+c
+c     blas zaxpy,zscal,izamax
+c     fortran dabs,max0,min0
+c
+c     internal variables
+c
+      complex*16 t
+      integer i,izamax,i0,j,ju,jz,j0,j1,k,kp1,l,lm,m,mm,nm1
+c
+      complex*16 zdum
+      double precision cabs1
+      double precision dreal,dimag
+      complex*16 zdumr,zdumi
+      dreal(zdumr) = zdumr
+      dimag(zdumi) = (0.0d0,-1.0d0)*zdumi
+      cabs1(zdum) = dabs(dreal(zdum)) + dabs(dimag(zdum))
+c
+      m = ml + mu + 1
+      info = 0
+c
+c     zero initial fill-in columns
+c
+      j0 = mu + 2
+      j1 = min0(n,m) - 1
+      if (j1 .lt. j0) go to 30
+      do 20 jz = j0, j1
+         i0 = m + 1 - jz
+         do 10 i = i0, ml
+            abd(i,jz) = (0.0d0,0.0d0)
+   10    continue
+   20 continue
+   30 continue
+      jz = j1
+      ju = 0
+c
+c     gaussian elimination with partial pivoting
+c
+      nm1 = n - 1
+      if (nm1 .lt. 1) go to 130
+      do 120 k = 1, nm1
+         kp1 = k + 1
+c
+c        zero next fill-in column
+c
+         jz = jz + 1
+         if (jz .gt. n) go to 50
+         if (ml .lt. 1) go to 50
+            do 40 i = 1, ml
+               abd(i,jz) = (0.0d0,0.0d0)
+   40       continue
+   50    continue
+c
+c        find l = pivot index
+c
+         lm = min0(ml,n-k)
+         l = izamax(lm+1,abd(m,k),1) + m - 1
+         ipvt(k) = l + k - m
+c
+c        zero pivot implies this column already triangularized
+c
+         if (cabs1(abd(l,k)) .eq. 0.0d0) go to 100
+c
+c           interchange if necessary
+c
+            if (l .eq. m) go to 60
+               t = abd(l,k)
+               abd(l,k) = abd(m,k)
+               abd(m,k) = t
+   60       continue
+c
+c           compute multipliers
+c
+            t = -(1.0d0,0.0d0)/abd(m,k)
+            call zscal(lm,t,abd(m+1,k),1)
+c
+c           row elimination with column indexing
+c
+            ju = min0(max0(ju,mu+ipvt(k)),n)
+            mm = m
+            if (ju .lt. kp1) go to 90
+            do 80 j = kp1, ju
+               l = l - 1
+               mm = mm - 1
+               t = abd(l,j)
+               if (l .eq. mm) go to 70
+                  abd(l,j) = abd(mm,j)
+                  abd(mm,j) = t
+   70          continue
+               call zaxpy(lm,t,abd(m+1,k),1,abd(mm+1,j),1)
+   80       continue
+   90       continue
+         go to 110
+  100    continue
+            info = k
+  110    continue
+  120 continue
+  130 continue
+      ipvt(n) = n
+      if (cabs1(abd(m,n)) .eq. 0.0d0) info = n
+      return
+      end

Property changes on: trunk/scipy/integrate/linpack_lite/zgbfa.f
___________________________________________________________________
Name: svn:eol-style
+ native

===================================================================
--- trunk/scipy/integrate/linpack_lite/zgbsl.f	2008-02-20 05:27:16 UTC (rev 3950)
+++ trunk/scipy/integrate/linpack_lite/zgbsl.f	2008-02-20 05:39:03 UTC (rev 3951)
@@ -0,0 +1,139 @@
+      subroutine zgbsl(abd,lda,n,ml,mu,ipvt,b,job)
+      integer lda,n,ml,mu,ipvt(1),job
+      complex*16 abd(lda,1),b(1)
+c
+c     zgbsl solves the complex*16 band system
+c     a * x = b  or  ctrans(a) * x = b
+c     using the factors computed by zgbco or zgbfa.
+c
+c     on entry
+c
+c        abd     complex*16(lda, n)
+c                the output from zgbco or zgbfa.
+c
+c        lda     integer
+c                the leading dimension of the array  abd .
+c
+c        n       integer
+c                the order of the original matrix.
+c
+c        ml      integer
+c                number of diagonals below the main diagonal.
+c
+c        mu      integer
+c                number of diagonals above the main diagonal.
+c
+c        ipvt    integer(n)
+c                the pivot vector from zgbco or zgbfa.
+c
+c        b       complex*16(n)
+c                the right hand side vector.
+c
+c        job     integer
+c                = 0         to solve  a*x = b ,
+c                = nonzero   to solve  ctrans(a)*x = b , where
+c                            ctrans(a)  is the conjugate transpose.
+c
+c     on return
+c
+c        b       the solution vector  x .
+c
+c     error condition
+c
+c        a division by zero will occur if the input factor contains a
+c        zero on the diagonal.  technically this indicates singularity
+c        but it is often caused by improper arguments or improper
+c        setting of lda .  it will not occur if the subroutines are
+c        called correctly and if zgbco has set rcond .gt. 0.0
+c        or zgbfa has set info .eq. 0 .
+c
+c     to compute  inverse(a) * c  where  c  is a matrix
+c     with  p  columns
+c           call zgbco(abd,lda,n,ml,mu,ipvt,rcond,z)
+c           if (rcond is too small) go to ...
+c           do 10 j = 1, p
+c              call zgbsl(abd,lda,n,ml,mu,ipvt,c(1,j),0)
+c        10 continue
+c
+c     linpack. this version dated 08/14/78 .
+c     cleve moler, university of new mexico, argonne national lab.
+c
+c     subroutines and functions
+c
+c     blas zaxpy,zdotc
+c     fortran dconjg,min0
+c
+c     internal variables
+c
+      complex*16 zdotc,t
+      integer k,kb,l,la,lb,lm,m,nm1
+      double precision dreal,dimag
+      complex*16 zdumr,zdumi
+      dreal(zdumr) = zdumr
+      dimag(zdumi) = (0.0d0,-1.0d0)*zdumi
+c
+      m = mu + ml + 1
+      nm1 = n - 1
+      if (job .ne. 0) go to 50
+c
+c        job = 0 , solve  a * x = b
+c        first solve l*y = b
+c
+         if (ml .eq. 0) go to 30
+         if (nm1 .lt. 1) go to 30
+            do 20 k = 1, nm1
+               lm = min0(ml,n-k)
+               l = ipvt(k)
+               t = b(l)
+               if (l .eq. k) go to 10
+                  b(l) = b(k)
+                  b(k) = t
+   10          continue
+               call zaxpy(lm,t,abd(m+1,k),1,b(k+1),1)
+   20       continue
+   30    continue
+c
+c        now solve  u*x = y
+c
+         do 40 kb = 1, n
+            k = n + 1 - kb
+            b(k) = b(k)/abd(m,k)
+            lm = min0(k,m) - 1
+            la = m - lm
+            lb = k - lm
+            t = -b(k)
+            call zaxpy(lm,t,abd(la,k),1,b(lb),1)
+   40    continue
+      go to 100
+   50 continue
+c
+c        job = nonzero, solve  ctrans(a) * x = b
+c        first solve  ctrans(u)*y = b
+c
+         do 60 k = 1, n
+            lm = min0(k,m) - 1
+            la = m - lm
+            lb = k - lm
+            t = zdotc(lm,abd(la,k),1,b(lb),1)
+            b(k) = (b(k) - t)/dconjg(abd(m,k))
+   60    continue
+c
+c        now solve ctrans(l)*x = y
+c
+         if (ml .eq. 0) go to 90
+         if (nm1 .lt. 1) go to 90
+            do 80 kb = 1, nm1
+               k = n - kb
+               lm = min0(ml,n-k)
+               b(k) = b(k) + zdotc(lm,abd(m+1,k),1,b(k+1),1)
+               l = ipvt(k)
+               if (l .eq. k) go to 70
+                  t = b(l)
+                  b(l) = b(k)
+                  b(k) = t
+   70          continue
+   80       continue
+   90    continue
+  100 continue
+      return
+      end

Property changes on: trunk/scipy/integrate/linpack_lite/zgbsl.f
___________________________________________________________________
Name: svn:eol-style
+ native

===================================================================
--- trunk/scipy/integrate/linpack_lite/zgefa.f	2008-02-20 05:27:16 UTC (rev 3950)
+++ trunk/scipy/integrate/linpack_lite/zgefa.f	2008-02-20 05:39:03 UTC (rev 3951)
@@ -0,0 +1,111 @@
+      subroutine zgefa(a,lda,n,ipvt,info)
+      integer lda,n,ipvt(1),info
+      complex*16 a(lda,1)
+c
+c     zgefa factors a complex*16 matrix by gaussian elimination.
+c
+c     zgefa is usually called by zgeco, but it can be called
+c     directly with a saving in time if  rcond  is not needed.
+c     (time for zgeco) = (1 + 9/n)*(time for zgefa) .
+c
+c     on entry
+c
+c        a       complex*16(lda, n)
+c                the matrix to be factored.
+c
+c        lda     integer
+c                the leading dimension of the array  a .
+c
+c        n       integer
+c                the order of the matrix  a .
+c
+c     on return
+c
+c        a       an upper triangular matrix and the multipliers
+c                which were used to obtain it.
+c                the factorization can be written  a = l*u  where
+c                l  is a product of permutation and unit lower
+c                triangular matrices and  u  is upper triangular.
+c
+c        ipvt    integer(n)
+c                an integer vector of pivot indices.
+c
+c        info    integer
+c                = 0  normal value.
+c                = k  if  u(k,k) .eq. 0.0 .  this is not an error
+c                     condition for this subroutine, but it does
+c                     indicate that zgesl or zgedi will divide by zero
+c                     if called.  use  rcond  in zgeco for a reliable
+c                     indication of singularity.
+c
+c     linpack. this version dated 08/14/78 .
+c     cleve moler, university of new mexico, argonne national lab.
+c
+c     subroutines and functions
+c
+c     blas zaxpy,zscal,izamax
+c     fortran dabs
+c
+c     internal variables
+c
+      complex*16 t
+      integer izamax,j,k,kp1,l,nm1
+c
+      complex*16 zdum
+      double precision cabs1
+      double precision dreal,dimag
+      complex*16 zdumr,zdumi
+      dreal(zdumr) = zdumr
+      dimag(zdumi) = (0.0d0,-1.0d0)*zdumi
+      cabs1(zdum) = dabs(dreal(zdum)) + dabs(dimag(zdum))
+c
+c     gaussian elimination with partial pivoting
+c
+      info = 0
+      nm1 = n - 1
+      if (nm1 .lt. 1) go to 70
+      do 60 k = 1, nm1
+         kp1 = k + 1
+c
+c        find l = pivot index
+c
+         l = izamax(n-k+1,a(k,k),1) + k - 1
+         ipvt(k) = l
+c
+c        zero pivot implies this column already triangularized
+c
+         if (cabs1(a(l,k)) .eq. 0.0d0) go to 40
+c
+c           interchange if necessary
+c
+            if (l .eq. k) go to 10
+               t = a(l,k)
+               a(l,k) = a(k,k)
+               a(k,k) = t
+   10       continue
+c
+c           compute multipliers
+c
+            t = -(1.0d0,0.0d0)/a(k,k)
+            call zscal(n-k,t,a(k+1,k),1)
+c
+c           row elimination with column indexing
+c
+            do 30 j = kp1, n
+               t = a(l,j)
+               if (l .eq. k) go to 20
+                  a(l,j) = a(k,j)
+                  a(k,j) = t
+   20          continue
+               call zaxpy(n-k,t,a(k+1,k),1,a(k+1,j),1)
+   30       continue
+         go to 50
+   40    continue
+            info = k
+   50    continue
+   60 continue
+   70 continue
+      ipvt(n) = n
+      if (cabs1(a(n,n)) .eq. 0.0d0) info = n
+      return
+      end

Property changes on: trunk/scipy/integrate/linpack_lite/zgefa.f
___________________________________________________________________
Name: svn:eol-style
+ native

===================================================================
--- trunk/scipy/integrate/linpack_lite/zgesl.f	2008-02-20 05:27:16 UTC (rev 3950)
+++ trunk/scipy/integrate/linpack_lite/zgesl.f	2008-02-20 05:39:03 UTC (rev 3951)
@@ -0,0 +1,122 @@
+      subroutine zgesl(a,lda,n,ipvt,b,job)
+      integer lda,n,ipvt(1),job
+      complex*16 a(lda,1),b(1)
+c
+c     zgesl solves the complex*16 system
+c     a * x = b  or  ctrans(a) * x = b
+c     using the factors computed by zgeco or zgefa.
+c
+c     on entry
+c
+c        a       complex*16(lda, n)
+c                the output from zgeco or zgefa.
+c
+c        lda     integer
+c                the leading dimension of the array  a .
+c
+c        n       integer
+c                the order of the matrix  a .
+c
+c        ipvt    integer(n)
+c                the pivot vector from zgeco or zgefa.
+c
+c        b       complex*16(n)
+c                the right hand side vector.
+c
+c        job     integer
+c                = 0         to solve  a*x = b ,
+c                = nonzero   to solve  ctrans(a)*x = b  where
+c                            ctrans(a)  is the conjugate transpose.
+c
+c     on return
+c
+c        b       the solution vector  x .
+c
+c     error condition
+c
+c        a division by zero will occur if the input factor contains a
+c        zero on the diagonal.  technically this indicates singularity
+c        but it is often caused by improper arguments or improper
+c        setting of lda .  it will not occur if the subroutines are
+c        called correctly and if zgeco has set rcond .gt. 0.0
+c        or zgefa has set info .eq. 0 .
+c
+c     to compute  inverse(a) * c  where  c  is a matrix
+c     with  p  columns
+c           call zgeco(a,lda,n,ipvt,rcond,z)
+c           if (rcond is too small) go to ...
+c           do 10 j = 1, p
+c              call zgesl(a,lda,n,ipvt,c(1,j),0)
+c        10 continue
+c
+c     linpack. this version dated 08/14/78 .
+c     cleve moler, university of new mexico, argonne national lab.
+c
+c     subroutines and functions
+c
+c     blas zaxpy,zdotc
+c     fortran dconjg
+c
+c     internal variables
+c
+      complex*16 zdotc,t
+      integer k,kb,l,nm1
+      double precision dreal,dimag
+      complex*16 zdumr,zdumi
+      dreal(zdumr) = zdumr
+      dimag(zdumi) = (0.0d0,-1.0d0)*zdumi
+c
+      nm1 = n - 1
+      if (job .ne. 0) go to 50
+c
+c        job = 0 , solve  a * x = b
+c        first solve  l*y = b
+c
+         if (nm1 .lt. 1) go to 30
+         do 20 k = 1, nm1
+            l = ipvt(k)
+            t = b(l)
+            if (l .eq. k) go to 10
+               b(l) = b(k)
+               b(k) = t
+   10       continue
+            call zaxpy(n-k,t,a(k+1,k),1,b(k+1),1)
+   20    continue
+   30    continue
+c
+c        now solve  u*x = y
+c
+         do 40 kb = 1, n
+            k = n + 1 - kb
+            b(k) = b(k)/a(k,k)
+            t = -b(k)
+            call zaxpy(k-1,t,a(1,k),1,b(1),1)
+   40    continue
+      go to 100
+   50 continue
+c
+c        job = nonzero, solve  ctrans(a) * x = b
+c        first solve  ctrans(u)*y = b
+c
+         do 60 k = 1, n
+            t = zdotc(k-1,a(1,k),1,b(1),1)
+            b(k) = (b(k) - t)/dconjg(a(k,k))
+   60    continue
+c
+c        now solve ctrans(l)*x = y
+c
+         if (nm1 .lt. 1) go to 90
+         do 80 kb = 1, nm1
+            k = n - kb
+            b(k) = b(k) + zdotc(n-k,a(k+1,k),1,b(k+1),1)
+            l = ipvt(k)
+            if (l .eq. k) go to 70
+               t = b(l)
+               b(l) = b(k)
+               b(k) = t
+   70       continue
+   80    continue
+   90    continue
+  100 continue
+      return
+      end

Property changes on: trunk/scipy/integrate/linpack_lite/zgesl.f
___________________________________________________________________
Name: svn:eol-style
+ native

===================================================================
--- trunk/scipy/integrate/odepack/zvode.f	2008-02-20 05:27:16 UTC (rev 3950)
+++ trunk/scipy/integrate/odepack/zvode.f	2008-02-20 05:39:03 UTC (rev 3951)
@@ -0,0 +1,3650 @@
+*DECK ZVODE
+      SUBROUTINE ZVODE (F, NEQ, Y, T, TOUT, ITOL, RTOL, ATOL, ITASK,
+     1            ISTATE, IOPT, ZWORK, LZW, RWORK, LRW, IWORK, LIW,
+     2            JAC, MF, RPAR, IPAR)
+      EXTERNAL F, JAC
+      DOUBLE COMPLEX Y, ZWORK
+      DOUBLE PRECISION T, TOUT, RTOL, ATOL, RWORK
+      INTEGER NEQ, ITOL, ITASK, ISTATE, IOPT, LZW, LRW, IWORK, LIW,
+     1        MF, IPAR
+      DIMENSION Y(*), RTOL(*), ATOL(*), ZWORK(LZW), RWORK(LRW),
+     1          IWORK(LIW), RPAR(*), IPAR(*)
+C-----------------------------------------------------------------------
+C ZVODE: Variable-coefficient Ordinary Differential Equation solver,
+C This version is in complex double precision.
+C
+C ZVODE solves the initial value problem for stiff or nonstiff
+C systems of first order ODEs,
+C     dy/dt = f(t,y) ,  or, in component form,
+C     dy(i)/dt = f(i) = f(i,t,y(1),y(2),...,y(NEQ)) (i = 1,...,NEQ).
+C Here the y vector is treated as complex.
+C ZVODE is a package based on the EPISODE and EPISODEB packages, and
+C on the ODEPACK user interface standard, with minor modifications.
+C
+C NOTE: When using ZVODE for a stiff system, it should only be used for
+C the case in which the function f is analytic, that is, when each f(i)
+C is an analytic function of each y(j).  Analyticity means that the
+C partial derivative df(i)/dy(j) is a unique complex number, and this
+C fact is critical in the way ZVODE solves the dense or banded linear
+C systems that arise in the stiff case.  For a complex stiff ODE system
+C in which f is not analytic, ZVODE is likely to have convergence
+C failures, and for this problem one should instead use DVODE on the
+C equivalent real system (in the real and imaginary parts of y).
+C-----------------------------------------------------------------------
+C Authors:
+C               Peter N. Brown and Alan C. Hindmarsh
+C               Center for Applied Scientific Computing
+C               Lawrence Livermore National Laboratory
+C               Livermore, CA 94551
+C and
+C               George D. Byrne (Prof. Emeritus)
+C               Illinois Institute of Technology
+C               Chicago, IL 60616
+C-----------------------------------------------------------------------
+C For references, see DVODE.
+C-----------------------------------------------------------------------
+C Summary of usage.
+C
+C Communication between the user and the ZVODE package, for normal
+C situations, is summarized here.  This summary describes only a subset
+C of the full set of options available.  See the full description for
+C details, including optional communication, nonstandard options,
+C problem (with program and output) following this summary.
+C
+C A. First provide a subroutine of the form:
+C           SUBROUTINE F (NEQ, T, Y, YDOT, RPAR, IPAR)
+C           DOUBLE COMPLEX Y(NEQ), YDOT(NEQ)
+C           DOUBLE PRECISION T
+C which supplies the vector function f by loading YDOT(i) with f(i).
+C
+C B. Next determine (or guess) whether or not the problem is stiff.
+C Stiffness occurs when the Jacobian matrix df/dy has an eigenvalue
+C whose real part is negative and large in magnitude, compared to the
+C reciprocal of the t span of interest.  If the problem is nonstiff,
+C use a method flag MF = 10.  If it is stiff, there are four standard
+C choices for MF (21, 22, 24, 25), and ZVODE requires the Jacobian
+C matrix in some form.  In these cases (MF .gt. 0), ZVODE will use a
+C saved copy of the Jacobian matrix.  If this is undesirable because of
+C storage limitations, set MF to the corresponding negative value
+C (-21, -22, -24, -25).  (See full description of MF below.)
+C The Jacobian matrix is regarded either as full (MF = 21 or 22),
+C or banded (MF = 24 or 25).  In the banded case, ZVODE requires two
+C half-bandwidth parameters ML and MU.  These are, respectively, the
+C widths of the lower and upper parts of the band, excluding the main
+C diagonal.  Thus the band consists of the locations (i,j) with
+C i-ML .le. j .le. i+MU, and the full bandwidth is ML+MU+1.
+C
+C C. If the problem is stiff, you are encouraged to supply the Jacobian
+C directly (MF = 21 or 24), but if this is not feasible, ZVODE will
+C compute it internally by difference quotients (MF = 22 or 25).
+C If you are supplying the Jacobian, provide a subroutine of the form:
+C           SUBROUTINE JAC (NEQ, T, Y, ML, MU, PD, NROWPD, RPAR, IPAR)
+C           DOUBLE COMPLEX Y(NEQ), PD(NROWPD,NEQ)
+C           DOUBLE PRECISION T
+C     For a full Jacobian (MF = 21), load PD(i,j) with df(i)/dy(j),
+C the partial derivative of f(i) with respect to y(j).  (Ignore the
+C ML and MU arguments in this case.)
+C     For a banded Jacobian (MF = 24), load PD(i-j+MU+1,j) with
+C df(i)/dy(j), i.e. load the diagonal lines of df/dy into the rows of
+C PD from the top down.
+C     In either case, only nonzero elements need be loaded.
+C
+C D. Write a main program which calls subroutine ZVODE once for
+C each point at which answers are desired.  This should also provide
+C for possible use of logical unit 6 for output of error messages
+C by ZVODE.  On the first call to ZVODE, supply arguments as follows:
+C F      = Name of subroutine for right-hand side vector f.
+C          This name must be declared external in calling program.
+C NEQ    = Number of first order ODEs.
+C Y      = Double complex array of initial values, of length NEQ.
+C T      = The initial value of the independent variable.
+C TOUT   = First point where output is desired (.ne. T).
+C ITOL   = 1 or 2 according as ATOL (below) is a scalar or array.
+C RTOL   = Relative tolerance parameter (scalar).
+C ATOL   = Absolute tolerance parameter (scalar or array).
+C          The estimated local error in Y(i) will be controlled so as
+C          to be roughly less (in magnitude) than
+C             EWT(i) = RTOL*abs(Y(i)) + ATOL     if ITOL = 1, or
+C             EWT(i) = RTOL*abs(Y(i)) + ATOL(i)  if ITOL = 2.
+C          Thus the local error test passes if, in each component,
+C          either the absolute error is less than ATOL (or ATOL(i)),
+C          or the relative error is less than RTOL.
+C          Use RTOL = 0.0 for pure absolute error control, and
+C          use ATOL = 0.0 (or ATOL(i) = 0.0) for pure relative error
+C          control.  Caution: Actual (global) errors may exceed these
+C          local tolerances, so choose them conservatively.
+C ITASK  = 1 for normal computation of output values of Y at t = TOUT.
+C ISTATE = Integer flag (input and output).  Set ISTATE = 1.
+C IOPT   = 0 to indicate no optional input used.
+C ZWORK  = Double precision complex work array of length at least:
+C             15*NEQ                      for MF = 10,
+C             8*NEQ + 2*NEQ**2            for MF = 21 or 22,
+C             10*NEQ + (3*ML + 2*MU)*NEQ  for MF = 24 or 25.
+C LZW    = Declared length of ZWORK (in user's DIMENSION statement).
+C RWORK  = Real work array of length at least 20 + NEQ.
+C LRW    = Declared length of RWORK (in user's DIMENSION statement).
+C IWORK  = Integer work array of length at least:
+C             30        for MF = 10,
+C             30 + NEQ  for MF = 21, 22, 24, or 25.
+C          If MF = 24 or 25, input in IWORK(1),IWORK(2) the lower
+C          and upper half-bandwidths ML,MU.
+C LIW    = Declared length of IWORK (in user's DIMENSION statement).
+C JAC    = Name of subroutine for Jacobian matrix (MF = 21 or 24).
+C          If used, this name must be declared external in calling
+C          program.  If not used, pass a dummy name.
+C MF     = Method flag.  Standard values are:
+C          10 for nonstiff (Adams) method, no Jacobian used.
+C          21 for stiff (BDF) method, user-supplied full Jacobian.
+C          22 for stiff method, internally generated full Jacobian.
+C          24 for stiff method, user-supplied banded Jacobian.
+C          25 for stiff method, internally generated banded Jacobian.
+C RPAR   = user-defined real or complex array passed to F and JAC.
+C IPAR   = user-defined integer array passed to F and JAC.
+C Note that the main program must declare arrays Y, ZWORK, RWORK, IWORK,
+C and possibly ATOL, RPAR, and IPAR.  RPAR may be declared REAL, DOUBLE,
+C COMPLEX, or DOUBLE COMPLEX, depending on the user's needs.
+C
+C E. The output from the first call (or any call) is:
+C      Y = Array of computed values of y(t) vector.
+C      T = Corresponding value of independent variable (normally TOUT).
+C ISTATE = 2  if ZVODE was successful, negative otherwise.
+C          -1 means excess work done on this call. (Perhaps wrong MF.)
+C          -2 means excess accuracy requested. (Tolerances too small.)
+C          -3 means illegal input detected. (See printed message.)
+C          -4 means repeated error test failures. (Check all input.)
+C          -5 means repeated convergence failures. (Perhaps bad
+C             Jacobian supplied or wrong choice of MF or tolerances.)
+C          -6 means error weight became zero during problem. (Solution
+C             component i vanished, and ATOL or ATOL(i) = 0.)
+C
+C F. To continue the integration after a successful return, simply
+C reset TOUT and call ZVODE again.  No other parameters need be reset.
+C
+C-----------------------------------------------------------------------
+C EXAMPLE PROBLEM
+C
+C The program below uses ZVODE to solve the following system of 2 ODEs:
+C dw/dt = -i*w*w*z, dz/dt = i*z; w(0) = 1/2.1, z(0) = 1; t = 0 to 2*pi.
+C Solution: w = 1/(z + 1.1), z = exp(it).  As z traces the unit circle,
+C w traces a circle of radius 10/2.1 with center at 11/2.1.
+C For convenience, Main passes RPAR = (imaginary unit i) to FEX and JEX.
+C
+C     EXTERNAL FEX, JEX
+C     DOUBLE COMPLEX Y(2), ZWORK(24), RPAR, WTRU, ERR
+C     DOUBLE PRECISION ABERR, AEMAX, ATOL, RTOL, RWORK(22), T, TOUT
+C     DIMENSION IWORK(32)
+C     NEQ = 2
+C     Y(1) = 1.0D0/2.1D0
+C     Y(2) = 1.0D0
+C     T = 0.0D0
+C     DTOUT = 0.1570796326794896D0
+C     TOUT = DTOUT
+C     ITOL = 1
+C     RTOL = 1.D-9
+C     ATOL = 1.D-8
+C     ISTATE = 1
+C     IOPT = 0
+C     LZW = 24
+C     LRW = 22
+C     LIW = 32
+C     MF = 21
+C     RPAR = DCMPLX(0.0D0,1.0D0)
+C     AEMAX = 0.0D0
+C     WRITE(6,10)
+C 10  FORMAT('   t',11X,'w',26X,'z')
+C     DO 40 IOUT = 1,40
+C    1             ZWORK,LZW,RWORK,LRW,IWORK,LIW,JEX,MF,RPAR,IPAR)
+C       WTRU = 1.0D0/DCMPLX(COS(T) + 1.1D0, SIN(T))
+C       ERR = Y(1) - WTRU
+C       ABERR = ABS(DREAL(ERR)) + ABS(DIMAG(ERR))
+C       AEMAX = MAX(AEMAX,ABERR)
+C       WRITE(6,20) T, DREAL(Y(1)),DIMAG(Y(1)), DREAL(Y(2)),DIMAG(Y(2))
+C 20    FORMAT(F9.5,2X,2F12.7,3X,2F12.7)
+C       IF (ISTATE .LT. 0) THEN
+C         WRITE(6,30) ISTATE
+C 30      FORMAT(//'***** Error halt.  ISTATE =',I3)
+C         STOP
+C         ENDIF
+C 40    TOUT = TOUT + DTOUT
+C     WRITE(6,50) IWORK(11), IWORK(12), IWORK(13), IWORK(20),
+C    1            IWORK(21), IWORK(22), IWORK(23), AEMAX
+C 50  FORMAT(/' No. steps =',I4,'   No. f-s =',I5,
+C    1        '   No. J-s =',I4,'   No. LU-s =',I4/
+C    2        ' No. nonlinear iterations =',I4/
+C    3        ' No. nonlinear convergence failures =',I4/
+C    4        ' No. error test failures =',I4/
+C    5        ' Max. abs. error in w =',D10.2)
+C     STOP
+C     END
+C
+C     SUBROUTINE FEX (NEQ, T, Y, YDOT, RPAR, IPAR)
+C     DOUBLE COMPLEX Y(NEQ), YDOT(NEQ), RPAR
+C     DOUBLE PRECISION T
+C     YDOT(1) = -RPAR*Y(1)*Y(1)*Y(2)
+C     YDOT(2) = RPAR*Y(2)
+C     RETURN
+C     END
+C
+C     SUBROUTINE JEX (NEQ, T, Y, ML, MU, PD, NRPD, RPAR, IPAR)
+C     DOUBLE COMPLEX Y(NEQ), PD(NRPD,NEQ), RPAR
+C     DOUBLE PRECISION T
+C     PD(1,1) = -2.0D0*RPAR*Y(1)*Y(2)
+C     PD(1,2) = -RPAR*Y(1)*Y(1)
+C     PD(2,2) = RPAR
+C     RETURN
+C     END
+C
+C The output of this example program is as follows:
+C
+C   t           w                          z
+C  0.15708     0.4763242  -0.0356919      0.9876884   0.1564345
+C  0.31416     0.4767322  -0.0718256      0.9510565   0.3090170
+C  0.47124     0.4774351  -0.1088651      0.8910065   0.4539906
+C  0.62832     0.4784699  -0.1473206      0.8090170   0.5877853
+C  0.78540     0.4798943  -0.1877789      0.7071067   0.7071069
+C  0.94248     0.4817938  -0.2309414      0.5877852   0.8090171
+C  1.09956     0.4842934  -0.2776778      0.4539904   0.8910066
+C  1.25664     0.4875766  -0.3291039      0.3090169   0.9510566
+C  1.41372     0.4919177  -0.3866987      0.1564343   0.9876884
+C  1.57080     0.4977376  -0.4524889     -0.0000001   1.0000000
+C  1.72788     0.5057044  -0.5293524     -0.1564346   0.9876883
+C  1.88496     0.5169274  -0.6215400     -0.3090171   0.9510565
+C  2.04204     0.5333540  -0.7356275     -0.4539906   0.8910065
+C  2.19911     0.5586542  -0.8823669     -0.5877854   0.8090169
+C  2.35619     0.6004188  -1.0806013     -0.7071069   0.7071067
+C  2.51327     0.6764486  -1.3664281     -0.8090171   0.5877851
+C  2.67035     0.8366909  -1.8175245     -0.8910066   0.4539904
+C  2.82743     1.2657121  -2.6260146     -0.9510566   0.3090168
+C  2.98451     3.0284506  -4.2182180     -0.9876884   0.1564343
+C  3.14159    10.0000699   0.0000663     -1.0000000  -0.0000002
+C  3.29867     3.0284170   4.2182053     -0.9876883  -0.1564346
+C  3.45575     1.2657041   2.6260067     -0.9510565  -0.3090172
+C  3.61283     0.8366878   1.8175205     -0.8910064  -0.4539907
+C  3.76991     0.6764469   1.3664259     -0.8090169  -0.5877854
+C  3.92699     0.6004178   1.0806000     -0.7071066  -0.7071069
+C  4.08407     0.5586535   0.8823662     -0.5877851  -0.8090171
+C  4.24115     0.5333535   0.7356271     -0.4539903  -0.8910066
+C  4.39823     0.5169271   0.6215398     -0.3090168  -0.9510566
+C  4.55531     0.5057041   0.5293523     -0.1564343  -0.9876884
+C  4.71239     0.4977374   0.4524890      0.0000002  -1.0000000
+C  4.86947     0.4919176   0.3866988      0.1564347  -0.9876883
+C  5.02655     0.4875765   0.3291040      0.3090172  -0.9510564
+C  5.18363     0.4842934   0.2776780      0.4539907  -0.8910064
+C  5.34071     0.4817939   0.2309415      0.5877854  -0.8090169
+C  5.49779     0.4798944   0.1877791      0.7071069  -0.7071066
+C  5.65487     0.4784700   0.1473208      0.8090171  -0.5877850
+C  5.81195     0.4774352   0.1088652      0.8910066  -0.4539903
+C  5.96903     0.4767324   0.0718257      0.9510566  -0.3090168
+C  6.12611     0.4763244   0.0356920      0.9876884  -0.1564342
+C  6.28319     0.4761907   0.0000000      1.0000000   0.0000003
+C
+C No. steps = 542   No. f-s =  610   No. J-s =  10   No. LU-s =  47
+C No. nonlinear iterations = 607
+C No. nonlinear convergence failures =   0
+C No. error test failures =  13
+C Max. abs. error in w =  0.13E-03
+C
+C-----------------------------------------------------------------------
+C Full description of user interface to ZVODE.
+C
+C The user interface to ZVODE consists of the following parts.
+C
+C i.   The call sequence to subroutine ZVODE, which is a driver
+C      routine for the solver.  This includes descriptions of both
+C      the call sequence arguments and of user-supplied routines.
+C      Following these descriptions is
+C        * a description of optional input available through the
+C          call sequence,
+C        * a description of optional output (in the work arrays), and
+C        * instructions for interrupting and restarting a solution.
+C
+C ii.  Descriptions of other routines in the ZVODE package that may be
+C      (optionally) called by the user.  These provide the ability to
+C      alter error message handling, save and restore the internal
+C      COMMON, and obtain specified derivatives of the solution y(t).
+C
+C iii. Descriptions of COMMON blocks to be declared in overlay
+C      or similar environments.
+C
+C iv.  Description of two routines in the ZVODE package, either of
+C      which the user may replace with his own version, if desired.
+C      these relate to the measurement of errors.
+C
+C-----------------------------------------------------------------------
+C Part i.  Call Sequence.
+C
+C The call sequence parameters used for input only are
+C     F, NEQ, TOUT, ITOL, RTOL, ATOL, ITASK, IOPT, LRW, LIW, JAC, MF,
+C and those used for both input and output are
+C     Y, T, ISTATE.
+C The work arrays ZWORK, RWORK, and IWORK are also used for conditional
+C and optional input and optional output.  (The term output here refers
+C to the return from subroutine ZVODE to the user's calling program.)
+C
+C The legality of input parameters will be thoroughly checked on the
+C initial call for the problem, but not checked thereafter unless a
+C change in input parameters is flagged by ISTATE = 3 in the input.
+C
+C The descriptions of the call arguments are as follows.
+C
+C F      = The name of the user-supplied subroutine defining the
+C          ODE system.  The system must be put in the first-order
+C          form dy/dt = f(t,y), where f is a vector-valued function
+C          of the scalar t and the vector y.  Subroutine F is to
+C          compute the function f.  It is to have the form
+C               SUBROUTINE F (NEQ, T, Y, YDOT, RPAR, IPAR)
+C               DOUBLE COMPLEX Y(NEQ), YDOT(NEQ)
+C               DOUBLE PRECISION T
+C          where NEQ, T, and Y are input, and the array YDOT = f(t,y)
+C          is output.  Y and YDOT are double complex arrays of length
+C          NEQ.  Subroutine F should not alter Y(1),...,Y(NEQ).
+C          F must be declared EXTERNAL in the calling program.
+C
+C          Subroutine F may access user-defined real/complex and
+C          integer work arrays RPAR and IPAR, which are to be
+C          dimensioned in the calling program.
+C
+C          If quantities computed in the F routine are needed
+C          externally to ZVODE, an extra call to F should be made
+C          for this purpose, for consistent and accurate results.
+C          If only the derivative dy/dt is needed, use ZVINDY instead.
+C
+C NEQ    = The size of the ODE system (number of first order
+C          ordinary differential equations).  Used only for input.
+C          NEQ may not be increased during the problem, but
+C          can be decreased (with ISTATE = 3 in the input).
+C
+C Y      = A double precision complex array for the vector of dependent
+C          variables, of length NEQ or more.  Used for both input and
+C          output on the first call (ISTATE = 1), and only for output
+C          on other calls.  On the first call, Y must contain the
+C          vector of initial values.  In the output, Y contains the
+C          computed solution evaluated at T.  If desired, the Y array
+C          may be used for other purposes between calls to the solver.
+C
+C          This array is passed as the Y argument in all calls to
+C          F and JAC.
+C
+C T      = The independent variable.  In the input, T is used only on
+C          the first call, as the initial point of the integration.
+C          In the output, after each call, T is the value at which a
+C          computed solution Y is evaluated (usually the same as TOUT).
+C          On an error return, T is the farthest point reached.
+C
+C TOUT   = The next value of t at which a computed solution is desired.
+C          Used only for input.
+C
+C          When starting the problem (ISTATE = 1), TOUT may be equal
+C          to T for one call, then should .ne. T for the next call.
+C          For the initial T, an input value of TOUT .ne. T is used
+C          in order to determine the direction of the integration
+C          (i.e. the algebraic sign of the step sizes) and the rough
+C          scale of the problem.  Integration in either direction
+C          (forward or backward in t) is permitted.
+C
+C          If ITASK = 2 or 5 (one-step modes), TOUT is ignored after
+C          the first call (i.e. the first call with TOUT .ne. T).
+C          Otherwise, TOUT is required on every call.
+C
+C          If ITASK = 1, 3, or 4, the values of TOUT need not be
+C          monotone, but a value of TOUT which backs up is limited
+C          to the current internal t interval, whose endpoints are
+C          TCUR - HU and TCUR.  (See optional output, below, for
+C          TCUR and HU.)
+C
+C ITOL   = An indicator for the type of error control.  See
+C          description below under ATOL.  Used only for input.
+C
+C RTOL   = A relative error tolerance parameter, either a scalar or
+C          an array of length NEQ.  See description below under ATOL.
+C          Input only.
+C
+C ATOL   = An absolute error tolerance parameter, either a scalar or
+C          an array of length NEQ.  Input only.
+C
+C          The input parameters ITOL, RTOL, and ATOL determine
+C          the error control performed by the solver.  The solver will
+C          control the vector e = (e(i)) of estimated local errors
+C          in Y, according to an inequality of the form
+C                      rms-norm of ( e(i)/EWT(i) )   .le.   1,
+C          where       EWT(i) = RTOL(i)*abs(Y(i)) + ATOL(i),
+C          and the rms-norm (root-mean-square norm) here is
+C          rms-norm(v) = sqrt(sum v(i)**2 / NEQ).  Here EWT = (EWT(i))
+C          is a vector of weights which must always be positive, and
+C          the values of RTOL and ATOL should all be non-negative.
+C          The following table gives the types (scalar/array) of
+C          RTOL and ATOL, and the corresponding form of EWT(i).
+C
+C             ITOL    RTOL       ATOL          EWT(i)
+C              1     scalar     scalar     RTOL*ABS(Y(i)) + ATOL
+C              2     scalar     array      RTOL*ABS(Y(i)) + ATOL(i)
+C              3     array      scalar     RTOL(i)*ABS(Y(i)) + ATOL
+C              4     array      array      RTOL(i)*ABS(Y(i)) + ATOL(i)
+C
+C          When either of these parameters is a scalar, it need not
+C          be dimensioned in the user's calling program.
+C
+C          If none of the above choices (with ITOL, RTOL, and ATOL
+C          fixed throughout the problem) is suitable, more general
+C          error controls can be obtained by substituting
+C          user-supplied routines for the setting of EWT and/or for
+C          the norm calculation.  See Part iv below.
+C
+C          If global errors are to be estimated by making a repeated
+C          run on the same problem with smaller tolerances, then all
+C          components of RTOL and ATOL (i.e. of EWT) should be scaled
+C          down uniformly.
+C
+C          Input only.  ITASK has the following values and meanings.
+C          1  means normal computation of output values of y(t) at
+C             t = TOUT (by overshooting and interpolating).
+C          2  means take one step only and return.
+C          3  means stop at the first internal mesh point at or
+C             beyond t = TOUT and return.
+C          4  means normal computation of output values of y(t) at
+C             t = TOUT but without overshooting t = TCRIT.
+C             TCRIT must be input as RWORK(1).  TCRIT may be equal to
+C             or beyond TOUT, but not behind it in the direction of
+C             integration.  This option is useful if the problem
+C             has a singularity at or beyond t = TCRIT.
+C          5  means take one step, without passing TCRIT, and return.
+C             TCRIT must be input as RWORK(1).
+C
+C          Note:  If ITASK = 4 or 5 and the solver reaches TCRIT
+C          (within roundoff), it will return T = TCRIT (exactly) to
+C          indicate this (unless ITASK = 4 and TOUT comes before TCRIT,
+C          in which case answers at T = TOUT are returned first).
+C
+C ISTATE = an index used for input and output to specify the
+C          the state of the calculation.
+C
+C          In the input, the values of ISTATE are as follows.
+C          1  means this is the first call for the problem
+C             (initializations will be done).  See note below.
+C          2  means this is not the first call, and the calculation
+C             is to continue normally, with no change in any input
+C             parameters except possibly TOUT and ITASK.
+C             (If ITOL, RTOL, and/or ATOL are changed between calls
+C             with ISTATE = 2, the new values will be used but not
+C             tested for legality.)
+C          3  means this is not the first call, and the
+C             calculation is to continue normally, but with
+C             a change in input parameters other than
+C             TOUT and ITASK.  Changes are allowed in
+C             NEQ, ITOL, RTOL, ATOL, IOPT, LRW, LIW, MF, ML, MU,
+C             and any of the optional input except H0.
+C             (See IWORK description for ML and MU.)
+C          Note:  A preliminary call with TOUT = T is not counted
+C          as a first call here, as no initialization or checking of
+C          input is done.  (Such a call is sometimes useful to include
+C          the initial conditions in the output.)
+C          Thus the first call for which TOUT .ne. T requires
+C          ISTATE = 1 in the input.
+C
+C          In the output, ISTATE has the following values and meanings.
+C           1  means nothing was done, as TOUT was equal to T with
+C              ISTATE = 1 in the input.
+C           2  means the integration was performed successfully.
+C          -1  means an excessive amount of work (more than MXSTEP
+C              steps) was done on this call, before completing the
+C              requested task, but the integration was otherwise
+C              successful as far as T.  (MXSTEP is an optional input
+C              and is normally 500.)  To continue, the user may
+C              simply reset ISTATE to a value .gt. 1 and call again.
+C              (The excess work step counter will be reset to 0.)
+C              In addition, the user may increase MXSTEP to avoid
+C              this error return.  (See optional input below.)
+C          -2  means too much accuracy was requested for the precision
+C              of the machine being used.  This was detected before
+C              completing the requested task, but the integration
+C              was successful as far as T.  To continue, the tolerance
+C              parameters must be reset, and ISTATE must be set
+C              to 3.  The optional output TOLSF may be used for this
+C              purpose.  (Note: If this condition is detected before
+C              taking any steps, then an illegal input return
+C              (ISTATE = -3) occurs instead.)
+C          -3  means illegal input was detected, before taking any
+C              integration steps.  See written message for details.
+C              Note:  If the solver detects an infinite loop of calls
+C              to the solver with illegal input, it will cause
+C              the run to stop.
+C          -4  means there were repeated error test failures on
+C              one attempted step, before completing the requested
+C              task, but the integration was successful as far as T.
+C              The problem may have a singularity, or the input
+C              may be inappropriate.
+C          -5  means there were repeated convergence test failures on
+C              one attempted step, before completing the requested
+C              task, but the integration was successful as far as T.
+C              This may be caused by an inaccurate Jacobian matrix,
+C              if one is being used.
+C          -6  means EWT(i) became zero for some i during the
+C              integration.  Pure relative error control (ATOL(i)=0.0)
+C              was requested on a variable which has now vanished.
+C              The integration was successful as far as T.
+C
+C          Note:  Since the normal output value of ISTATE is 2,
+C          it does not need to be reset for normal continuation.
+C          Also, since a negative input value of ISTATE will be
+C          regarded as illegal, a negative output value requires the
+C          user to change it, and possibly other input, before
+C          calling the solver again.
+C
+C IOPT   = An integer flag to specify whether or not any optional
+C          input is being used on this call.  Input only.
+C          The optional input is listed separately below.
+C          IOPT = 0 means no optional input is being used.
+C                   Default values will be used in all cases.
+C          IOPT = 1 means optional input is being used.
+C
+C ZWORK  = A double precision complex working array.
+C          The length of ZWORK must be at least
+C             NYH*(MAXORD + 1) + 2*NEQ + LWM    where
+C          NYH    = the initial value of NEQ,
+C          MAXORD = 12 (if METH = 1) or 5 (if METH = 2) (unless a
+C                   smaller value is given as an optional input),
+C          LWM = length of work space for matrix-related data:
+C          LWM = 0             if MITER = 0,
+C          LWM = 2*NEQ**2      if MITER = 1 or 2, and MF.gt.0,
+C          LWM = NEQ**2        if MITER = 1 or 2, and MF.lt.0,
+C          LWM = NEQ           if MITER = 3,
+C          LWM = (3*ML+2*MU+2)*NEQ     if MITER = 4 or 5, and MF.gt.0,
+C          LWM = (2*ML+MU+1)*NEQ       if MITER = 4 or 5, and MF.lt.0.
+C          (See the MF description for METH and MITER.)
+C          Thus if MAXORD has its default value and NEQ is constant,
+C          this length is:
+C             15*NEQ                    for MF = 10,
+C             15*NEQ + 2*NEQ**2         for MF = 11 or 12,
+C             15*NEQ + NEQ**2           for MF = -11 or -12,
+C             16*NEQ                    for MF = 13,
+C             17*NEQ + (3*ML+2*MU)*NEQ  for MF = 14 or 15,
+C             16*NEQ + (2*ML+MU)*NEQ    for MF = -14 or -15,
+C              8*NEQ                    for MF = 20,
+C              8*NEQ + 2*NEQ**2         for MF = 21 or 22,
+C              8*NEQ + NEQ**2           for MF = -21 or -22,
+C              9*NEQ                    for MF = 23,
+C             10*NEQ + (3*ML+2*MU)*NEQ  for MF = 24 or 25.
+C              9*NEQ + (2*ML+MU)*NEQ    for MF = -24 or -25.
+C
+C LZW    = The length of the array ZWORK, as declared by the user.
+C          (This will be checked by the solver.)
+C
+C RWORK  = A real working array (double precision).
+C          The length of RWORK must be at least 20 + NEQ.
+C          The first 20 words of RWORK are reserved for conditional
+C          and optional input and optional output.
+C
+C          The following word in RWORK is a conditional input:
+C            RWORK(1) = TCRIT = critical value of t which the solver
+C                       is not to overshoot.  Required if ITASK is
+C                       4 or 5, and ignored otherwise.  (See ITASK.)
+C
+C LRW    = The length of the array RWORK, as declared by the user.
+C          (This will be checked by the solver.)
+C
+C IWORK  = An integer work array.  The length of IWORK must be at least
+C             30        if MITER = 0 or 3 (MF = 10, 13, 20, 23), or
+C             30 + NEQ  otherwise (abs(MF) = 11,12,14,15,21,22,24,25).
+C          The first 30 words of IWORK are reserved for conditional and
+C          optional input and optional output.
+C
+C          The following 2 words in IWORK are conditional input:
+C            IWORK(1) = ML     These are the lower and upper
+C            IWORK(2) = MU     half-bandwidths, respectively, of the
+C                       banded Jacobian, excluding the main diagonal.
+C                       The band is defined by the matrix locations
+C                       (i,j) with i-ML .le. j .le. i+MU.  ML and MU
+C                       must satisfy  0 .le.  ML,MU  .le. NEQ-1.
+C                       These are required if MITER is 4 or 5, and
+C                       ignored otherwise.  ML and MU may in fact be
+C                       the band parameters for a matrix to which
+C                       df/dy is only approximately equal.
+C
+C LIW    = the length of the array IWORK, as declared by the user.
+C          (This will be checked by the solver.)
+C
+C Note:  The work arrays must not be altered between calls to ZVODE
+C for the same problem, except possibly for the conditional and
+C optional input, and except for the last 2*NEQ words of ZWORK and
+C the last NEQ words of RWORK.  The latter space is used for internal
+C scratch space, and so is available for use by the user outside ZVODE
+C between calls, if desired (but not for use by F or JAC).
+C
+C JAC    = The name of the user-supplied routine (MITER = 1 or 4) to
+C          compute the Jacobian matrix, df/dy, as a function of
+C          the scalar t and the vector y.  It is to have the form
+C               SUBROUTINE JAC (NEQ, T, Y, ML, MU, PD, NROWPD,
+C                               RPAR, IPAR)
+C               DOUBLE COMPLEX Y(NEQ), PD(NROWPD,NEQ)
+C               DOUBLE PRECISION T
+C          where NEQ, T, Y, ML, MU, and NROWPD are input and the array
+C          PD is to be loaded with partial derivatives (elements of the
+C          Jacobian matrix) in the output.  PD must be given a first
+C          dimension of NROWPD.  T and Y have the same meaning as in
+C          Subroutine F.
+C               In the full matrix case (MITER = 1), ML and MU are
+C          ignored, and the Jacobian is to be loaded into PD in
+C          columnwise manner, with df(i)/dy(j) loaded into PD(i,j).
+C               In the band matrix case (MITER = 4), the elements
+C          within the band are to be loaded into PD in columnwise
+C          manner, with diagonal lines of df/dy loaded into the rows
+C          of PD. Thus df(i)/dy(j) is to be loaded into PD(i-j+MU+1,j).
+C          ML and MU are the half-bandwidth parameters. (See IWORK).
+C          The locations in PD in the two triangular areas which
+C          correspond to nonexistent matrix elements can be ignored
+C          or loaded arbitrarily, as they are overwritten by ZVODE.
+C               JAC need not provide df/dy exactly.  A crude
+C          approximation (possibly with a smaller bandwidth) will do.
+C               In either case, PD is preset to zero by the solver,
+C          so that only the nonzero elements need be loaded by JAC.
+C          Each call to JAC is preceded by a call to F with the same
+C          arguments NEQ, T, and Y.  Thus to gain some efficiency,
+C          intermediate quantities shared by both calculations may be
+C          saved in a user COMMON block by F and not recomputed by JAC,
+C          if desired.  Also, JAC may alter the Y array, if desired.
+C          JAC must be declared external in the calling program.
+C               Subroutine JAC may access user-defined real/complex and
+C          integer work arrays, RPAR and IPAR, whose dimensions are set
+C          by the user in the calling program.
+C
+C MF     = The method flag.  Used only for input.  The legal values of
+C          MF are 10, 11, 12, 13, 14, 15, 20, 21, 22, 23, 24, 25,
+C          -11, -12, -14, -15, -21, -22, -24, -25.
+C          MF is a signed two-digit integer, MF = JSV*(10*METH + MITER).
+C          JSV = SIGN(MF) indicates the Jacobian-saving strategy:
+C            JSV =  1 means a copy of the Jacobian is saved for reuse
+C                     in the corrector iteration algorithm.
+C            JSV = -1 means a copy of the Jacobian is not saved
+C                     (valid only for MITER = 1, 2, 4, or 5).
+C          METH indicates the basic linear multistep method:
+C            METH = 1 means the implicit Adams method.
+C            METH = 2 means the method based on backward
+C                     differentiation formulas (BDF-s).
+C          MITER indicates the corrector iteration method:
+C            MITER = 0 means functional iteration (no Jacobian matrix
+C                      is involved).
+C            MITER = 1 means chord iteration with a user-supplied
+C                      full (NEQ by NEQ) Jacobian.
+C            MITER = 2 means chord iteration with an internally
+C                      generated (difference quotient) full Jacobian
+C                      (using NEQ extra calls to F per df/dy value).
+C            MITER = 3 means chord iteration with an internally
+C                      generated diagonal Jacobian approximation
+C                      (using 1 extra call to F per df/dy evaluation).
+C            MITER = 4 means chord iteration with a user-supplied
+C                      banded Jacobian.
+C            MITER = 5 means chord iteration with an internally
+C                      generated banded Jacobian (using ML+MU+1 extra
+C                      calls to F per df/dy evaluation).
+C          If MITER = 1 or 4, the user must supply a subroutine JAC
+C          (the name is arbitrary) as described above under JAC.
+C          For other values of MITER, a dummy argument can be used.
+C
+C RPAR     User-specified array used to communicate real or complex
+C          parameters to user-supplied subroutines.  If RPAR is an
+C          array, it must be dimensioned in the user's calling program;
+C          if it is unused or it is a scalar, then it need not be
+C          dimensioned.  The type of RPAR may be REAL, DOUBLE, COMPLEX,
+C          or DOUBLE COMPLEX, depending on the user program's needs.
+C          RPAR is not type-declared within ZVODE, but simply passed
+C          (by address) to the user's F and JAC routines.
+C
+C IPAR     User-specified array used to communicate integer parameter
+C          to user-supplied subroutines.  If IPAR is an array, it must
+C          be dimensioned in the user's calling program.
+C-----------------------------------------------------------------------
+C Optional Input.
+C
+C The following is a list of the optional input provided for in the
+C call sequence.  (See also Part ii.)  For each such input variable,
+C this table lists its name as used in this documentation, its
+C location in the call sequence, its meaning, and the default value.
+C The use of any of this input requires IOPT = 1, and in that
+C case all of this input is examined.  A value of zero for any
+C of these optional input variables will cause the default value to be
+C used.  Thus to use a subset of the optional input, simply preload
+C locations 5 to 10 in RWORK and IWORK to 0.0 and 0 respectively, and
+C then set those of interest to nonzero values.
+C
+C NAME    LOCATION      MEANING AND DEFAULT VALUE
+C
+C H0      RWORK(5)  The step size to be attempted on the first step.
+C                   The default value is determined by the solver.
+C
+C HMAX    RWORK(6)  The maximum absolute step size allowed.
+C                   The default value is infinite.
+C
+C HMIN    RWORK(7)  The minimum absolute step size allowed.
+C                   The default value is 0.  (This lower bound is not
+C                   enforced on the final step before reaching TCRIT
+C                   when ITASK = 4 or 5.)
+C
+C MAXORD  IWORK(5)  The maximum order to be allowed.  The default
+C                   value is 12 if METH = 1, and 5 if METH = 2.
+C                   If MAXORD exceeds the default value, it will
+C                   be reduced to the default value.
+C                   If MAXORD is changed during the problem, it may
+C                   cause the current order to be reduced.
+C
+C MXSTEP  IWORK(6)  Maximum number of (internally defined) steps
+C                   allowed during one call to the solver.
+C                   The default value is 500.
+C
+C MXHNIL  IWORK(7)  Maximum number of messages printed (per problem)
+C                   warning that T + H = T on a step (H = step size).
+C                   This must be positive to result in a non-default
+C                   value.  The default value is 10.
+C
+C-----------------------------------------------------------------------
+C Optional Output.
+C
+C As optional additional output from ZVODE, the variables listed
+C below are quantities related to the performance of ZVODE
+C which are available to the user.  These are communicated by way of
+C the work arrays, but also have internal mnemonic names as shown.
+C Except where stated otherwise, all of this output is defined
+C on any successful return from ZVODE, and on any return with
+C ISTATE = -1, -2, -4, -5, or -6.  On an illegal input return
+C (ISTATE = -3), they will be unchanged from their existing values
+C (if any), except possibly for TOLSF, LENZW, LENRW, and LENIW.
+C On any error return, output relevant to the error will be defined,
+C as noted below.
+C
+C NAME    LOCATION      MEANING
+C
+C HU      RWORK(11) The step size in t last used (successfully).
+C
+C HCUR    RWORK(12) The step size to be attempted on the next step.
+C
+C TCUR    RWORK(13) The current value of the independent variable
+C                   which the solver has actually reached, i.e. the
+C                   current internal mesh point in t.  In the output,
+C                   TCUR will always be at least as far from the
+C                   initial value of t as the current argument T,
+C                   but may be farther (if interpolation was done).
+C
+C TOLSF   RWORK(14) A tolerance scale factor, greater than 1.0,
+C                   computed when a request for too much accuracy was
+C                   detected (ISTATE = -3 if detected at the start of
+C                   the problem, ISTATE = -2 otherwise).  If ITOL is
+C                   left unaltered but RTOL and ATOL are uniformly
+C                   scaled up by a factor of TOLSF for the next call,
+C                   then the solver is deemed likely to succeed.
+C                   (The user may also ignore TOLSF and alter the
+C                   tolerance parameters in any other way appropriate.)
+C
+C NST     IWORK(11) The number of steps taken for the problem so far.
+C
+C NFE     IWORK(12) The number of f evaluations for the problem so far.
+C
+C NJE     IWORK(13) The number of Jacobian evaluations so far.
+C
+C NQU     IWORK(14) The method order last used (successfully).
+C
+C NQCUR   IWORK(15) The order to be attempted on the next step.
+C
+C IMXER   IWORK(16) The index of the component of largest magnitude in
+C                   the weighted local error vector ( e(i)/EWT(i) ),
+C                   on an error return with ISTATE = -4 or -5.
+C
+C LENZW   IWORK(17) The length of ZWORK actually required.
+C                   This is defined on normal returns and on an illegal
+C                   input return for insufficient storage.
+C
+C LENRW   IWORK(18) The length of RWORK actually required.
+C                   This is defined on normal returns and on an illegal
+C                   input return for insufficient storage.
+C
+C LENIW   IWORK(19) The length of IWORK actually required.
+C                   This is defined on normal returns and on an illegal
+C                   input return for insufficient storage.
+C
+C NLU     IWORK(20) The number of matrix LU decompositions so far.
+C
+C NNI     IWORK(21) The number of nonlinear (Newton) iterations so far.
+C
+C NCFN    IWORK(22) The number of convergence failures of the nonlinear
+C                   solver so far.
+C
+C NETF    IWORK(23) The number of error test failures of the integrator
+C                   so far.
+C
+C The following two arrays are segments of the ZWORK array which
+C may also be of interest to the user as optional output.
+C For each array, the table below gives its internal name,
+C its base address in ZWORK, and its description.
+C
+C
+C YH       1             The Nordsieck history array, of size NYH by
+C                        (NQCUR + 1), where NYH is the initial value
+C                        of NEQ.  For j = 0,1,...,NQCUR, column j+1
+C                        of YH contains HCUR**j/factorial(j) times
+C                        the j-th derivative of the interpolating
+C                        polynomial currently representing the
+C                        solution, evaluated at t = TCUR.
+C
+C ACOR     LENZW-NEQ+1   Array of size NEQ used for the accumulated
+C                        corrections on each step, scaled in the output
+C                        to represent the estimated local error in Y
+C                        on the last step.  This is the vector e in
+C                        the description of the error control.  It is
+C                        defined only on a successful return from ZVODE.
+C
+C-----------------------------------------------------------------------
+C Interrupting and Restarting
+C
+C If the integration of a given problem by ZVODE is to be
+C interrrupted and then later continued, such as when restarting
+C an interrupted run or alternating between two or more ODE problems,
+C the user should save, following the return from the last ZVODE call
+C prior to the interruption, the contents of the call sequence
+C variables and internal COMMON blocks, and later restore these
+C values before the next ZVODE call for that problem.  To save
+C and restore the COMMON blocks, use subroutine ZVSRCO, as
+C described below in part ii.
+C
+C In addition, if non-default values for either LUN or MFLAG are
+C desired, an extra call to XSETUN and/or XSETF should be made just
+C before continuing the integration.  See Part ii below for details.
+C
+C-----------------------------------------------------------------------
+C Part ii.  Other Routines Callable.
+C
+C The following are optional calls which the user may make to
+C gain additional capabilities in conjunction with ZVODE.
+C (The routines XSETUN and XSETF are designed to conform to the
+C SLATEC error handling package.)
+C
+C     FORM OF CALL                  FUNCTION
+C  CALL XSETUN(LUN)           Set the logical unit number, LUN, for
+C                             output of messages from ZVODE, if
+C                             the default is not desired.
+C                             The default value of LUN is 6.
+C
+C  CALL XSETF(MFLAG)          Set a flag to control the printing of
+C                             messages by ZVODE.
+C                             MFLAG = 0 means do not print. (Danger:
+C                             This risks losing valuable information.)
+C                             MFLAG = 1 means print (the default).
+C
+C                             Either of the above calls may be made at
+C                             any time and will take effect immediately.
+C
+C  CALL ZVSRCO(RSAV,ISAV,JOB) Saves and restores the contents of
+C                             the internal COMMON blocks used by
+C                             ZVODE. (See Part iii below.)
+C                             RSAV must be a real array of length 51
+C                             or more, and ISAV must be an integer
+C                             array of length 40 or more.
+C                             JOB=1 means save COMMON into RSAV/ISAV.
+C                             JOB=2 means restore COMMON from RSAV/ISAV.
+C                                ZVSRCO is useful if one is
+C                             interrupting a run and restarting
+C                             later, or alternating between two or
+C                             more problems solved with ZVODE.
+C
+C  CALL ZVINDY(,,,,,)         Provide derivatives of y, of various
+C        (See below.)         orders, at a specified point T, if
+C                             desired.  It may be called only after
+C                             a successful return from ZVODE.
+C
+C The detailed instructions for using ZVINDY are as follows.
+C The form of the call is:
+C
+C  CALL ZVINDY (T, K, ZWORK, NYH, DKY, IFLAG)
+C
+C The input parameters are:
+C
+C T         = Value of independent variable where answers are desired
+C             (normally the same as the T last returned by ZVODE).
+C             For valid results, T must lie between TCUR - HU and TCUR.
+C             (See optional output for TCUR and HU.)
+C K         = Integer order of the derivative desired.  K must satisfy
+C             0 .le. K .le. NQCUR, where NQCUR is the current order
+C             (see optional output).  The capability corresponding
+C             to K = 0, i.e. computing y(T), is already provided
+C             by ZVODE directly.  Since NQCUR .ge. 1, the first
+C             derivative dy/dt is always available with ZVINDY.
+C ZWORK     = The history array YH.
+C NYH       = Column length of YH, equal to the initial value of NEQ.
+C
+C The output parameters are:
+C
+C DKY       = A double complex array of length NEQ containing the
+C             computed value of the K-th derivative of y(t).
+C IFLAG     = Integer flag, returned as 0 if K and T were legal,
+C             -1 if K was illegal, and -2 if T was illegal.
+C             On an error return, a message is also written.
+C-----------------------------------------------------------------------
+C Part iii.  COMMON Blocks.
+C If ZVODE is to be used in an overlay situation, the user
+C must declare, in the primary overlay, the variables in:
+C   (1) the call sequence to ZVODE,
+C   (2) the two internal COMMON blocks
+C         /ZVOD01/  of length  83  (50 double precision words
+C                         followed by 33 integer words),
+C         /ZVOD02/  of length  9  (1 double precision word
+C                         followed by 8 integer words),
+C
+C If ZVODE is used on a system in which the contents of internal
+C COMMON blocks are not preserved between calls, the user should
+C declare the above two COMMON blocks in his calling program to insure
+C that their contents are preserved.
+C
+C-----------------------------------------------------------------------
+C Part iv.  Optionally Replaceable Solver Routines.
+C
+C Below are descriptions of two routines in the ZVODE package which
+C relate to the measurement of errors.  Either routine can be
+C replaced by a user-supplied version, if desired.  However, since such
+C a replacement may have a major impact on performance, it should be
+C done only when absolutely necessary, and only with great caution.
+C (Note: The means by which the package version of a routine is
+C superseded by the user's version may be system-dependent.)
+C
+C (a) ZEWSET.
+C The following subroutine is called just before each internal
+C integration step, and sets the array of error weights, EWT, as
+C described under ITOL/RTOL/ATOL above:
+C     SUBROUTINE ZEWSET (NEQ, ITOL, RTOL, ATOL, YCUR, EWT)
+C where NEQ, ITOL, RTOL, and ATOL are as in the ZVODE call sequence,
+C YCUR contains the current (double complex) dependent variable vector,
+C and EWT is the array of weights set by ZEWSET.
+C
+C If the user supplies this subroutine, it must return in EWT(i)
+C (i = 1,...,NEQ) a positive quantity suitable for comparison with
+C errors in Y(i).  The EWT array returned by ZEWSET is passed to the
+C ZVNORM routine (See below.), and also used by ZVODE in the computation
+C of the optional output IMXER, the diagonal Jacobian approximation,
+C and the increments for difference quotient Jacobians.
+C
+C In the user-supplied version of ZEWSET, it may be desirable to use
+C the current values of derivatives of y.  Derivatives up to order NQ
+C are available from the history array YH, described above under
+C Optional Output.  In ZEWSET, YH is identical to the YCUR array,
+C extended to NQ + 1 columns with a column length of NYH and scale
+C factors of h**j/factorial(j).  On the first call for the problem,
+C given by NST = 0, NQ is 1 and H is temporarily set to 1.0.
+C NYH is the initial value of NEQ.  The quantities NQ, H, and NST
+C can be obtained by including in ZEWSET the statements:
+C     DOUBLE PRECISION RVOD, H, HU
+C     COMMON /ZVOD01/ RVOD(50), IVOD(33)
+C     COMMON /ZVOD02/ HU, NCFN, NETF, NFE, NJE, NLU, NNI, NQU, NST
+C     NQ = IVOD(28)
+C     H = RVOD(21)
+C Thus, for example, the current value of dy/dt can be obtained as
+C YCUR(NYH+i)/H  (i=1,...,NEQ)  (and the division by H is
+C unnecessary when NST = 0).
+C
+C (b) ZVNORM.
+C The following is a real function routine which computes the weighted
+C root-mean-square norm of a vector v:
+C     D = ZVNORM (N, V, W)
+C where:
+C   N = the length of the vector,
+C   V = double complex array of length N containing the vector,
+C   W = real array of length N containing weights,
+C   D = sqrt( (1/N) * sum(abs(V(i))*W(i))**2 ).
+C ZVNORM is called with N = NEQ and with W(i) = 1.0/EWT(i), where
+C EWT is as set by subroutine ZEWSET.
+C
+C If the user supplies this function, it should return a non-negative
+C value of ZVNORM suitable for use in the error control in ZVODE.
+C None of the arguments should be altered by ZVNORM.
+C For example, a user-supplied ZVNORM routine might:
+C   -substitute a max-norm of (V(i)*W(i)) for the rms-norm, or
+C   -ignore some components of V in the norm, with the effect of
+C    suppressing the error control on those components of Y.
+C-----------------------------------------------------------------------
+C REVISION HISTORY (YYYYMMDD)
+C  20060517  DATE WRITTEN, modified from DVODE of 20020430.
+C  20061227  Added note on use for analytic f.
+C-----------------------------------------------------------------------
+C Other Routines in the ZVODE Package.
+C
+C In addition to Subroutine ZVODE, the ZVODE package includes the
+C following subroutines and function routines:
+C  ZVHIN     computes an approximate step size for the initial step.
+C  ZVINDY    computes an interpolated value of the y vector at t = TOUT.
+C  ZVSTEP    is the core integrator, which does one step of the
+C            integration and the associated error control.
+C  ZVSET     sets all method coefficients and test constants.
+C  ZVNLSD    solves the underlying nonlinear system -- the corrector.
+C  ZVJAC     computes and preprocesses the Jacobian matrix J = df/dy
+C            and the Newton iteration matrix P = I - (h/l1)*J.
+C  ZVSOL     manages solution of linear system in chord iteration.
+C  ZVJUST    adjusts the history array on a change of order.
+C  ZEWSET    sets the error weight vector EWT before each step.
+C  ZVNORM    computes the weighted r.m.s. norm of a vector.
+C  ZABSSQ    computes the squared absolute value of a double complex z.
+C  ZVSRCO    is a user-callable routine to save and restore
+C            the contents of the internal COMMON blocks.
+C  ZACOPY    is a routine to copy one two-dimensional array to another.
+C  ZGEFA and ZGESL   are routines from LINPACK for solving full
+C            systems of linear algebraic equations.
+C  ZGBFA and ZGBSL   are routines from LINPACK for solving banded
+C            linear systems.
+C  DZSCAL    scales a double complex array by a double prec. scalar.
+C  DZAXPY    adds a D.P. scalar times one complex vector to another.
+C  ZCOPY     is a basic linear algebra module from the BLAS.
+C  DUMACH    sets the unit roundoff of the machine.
+C  XERRWD, XSETUN, XSETF, IXSAV, and IUMACH handle the printing of all
+C            error messages and warnings.  XERRWD is machine-dependent.
+C Note: ZVNORM, ZABSSQ, DUMACH, IXSAV, and IUMACH are function routines.
+C All the others are subroutines.
+C The intrinsic functions called with double precision complex arguments
+C are: ABS, DREAL, and DIMAG.  All of these are expected to return
+C double precision real values.
+C
+C-----------------------------------------------------------------------
+C
+C Type declarations for labeled COMMON block ZVOD01 --------------------
+C
+      DOUBLE PRECISION ACNRM, CCMXJ, CONP, CRATE, DRC, EL,
+     1     ETA, ETAMAX, H, HMIN, HMXI, HNEW, HRL1, HSCAL, PRL1,
+     2     RC, RL1, SRUR, TAU, TQ, TN, UROUND
+      INTEGER ICF, INIT, IPUP, JCUR, JSTART, JSV, KFLAG, KUTH,
+     1        L, LMAX, LYH, LEWT, LACOR, LSAVF, LWM, LIWM,
+     2        LOCJS, MAXORD, METH, MITER, MSBJ, MXHNIL, MXSTEP,
+     3        N, NEWH, NEWQ, NHNIL, NQ, NQNYH, NQWAIT, NSLJ,
+     4        NSLP, NYH
+C
+C Type declarations for labeled COMMON block ZVOD02 --------------------
+C
+      DOUBLE PRECISION HU
+      INTEGER NCFN, NETF, NFE, NJE, NLU, NNI, NQU, NST
+C
+C Type declarations for local variables --------------------------------
+C
+      EXTERNAL ZVNLSD
+      LOGICAL IHIT
+      DOUBLE PRECISION ATOLI, BIG, EWTI, FOUR, H0, HMAX, HMX, HUN, ONE,
+     1   PT2, RH, RTOLI, SIZE, TCRIT, TNEXT, TOLSF, TP, TWO, ZERO
+      INTEGER I, IER, IFLAG, IMXER, JCO, KGO, LENIW, LENJ, LENP, LENZW,
+     1   LENRW, LENWM, LF0, MBAND, MFA, ML, MORD, MU, MXHNL0, MXSTP0,
+     2   NITER, NSLAST
+      CHARACTER*80 MSG
+C
+C Type declaration for function subroutines called ---------------------
+C
+      DOUBLE PRECISION DUMACH, ZVNORM
+C
+      DIMENSION MORD(2)
+C-----------------------------------------------------------------------
+C The following Fortran-77 declaration is to cause the values of the
+C listed (local) variables to be saved between calls to ZVODE.
+C-----------------------------------------------------------------------
+      SAVE MORD, MXHNL0, MXSTP0
+      SAVE ZERO, ONE, TWO, FOUR, PT2, HUN
+C-----------------------------------------------------------------------
+C The following internal COMMON blocks contain variables which are
+C communicated between subroutines in the ZVODE package, or which are
+C to be saved between calls to ZVODE.
+C In each block, real variables precede integers.
+C The block /ZVOD01/ appears in subroutines ZVODE, ZVINDY, ZVSTEP,
+C ZVSET, ZVNLSD, ZVJAC, ZVSOL, ZVJUST and ZVSRCO.
+C The block /ZVOD02/ appears in subroutines ZVODE, ZVINDY, ZVSTEP,
+C ZVNLSD, ZVJAC, and ZVSRCO.
+C
+C The variables stored in the internal COMMON blocks are as follows:
+C
+C ACNRM  = Weighted r.m.s. norm of accumulated correction vectors.
+C CCMXJ  = Threshhold on DRC for updating the Jacobian. (See DRC.)
+C CONP   = The saved value of TQ(5).
+C CRATE  = Estimated corrector convergence rate constant.
+C DRC    = Relative change in H*RL1 since last ZVJAC call.
+C EL     = Real array of integration coefficients.  See ZVSET.
+C ETA    = Saved tentative ratio of new to old H.
+C ETAMAX = Saved maximum value of ETA to be allowed.
+C H      = The step size.
+C HMIN   = The minimum absolute value of the step size H to be used.
+C HMXI   = Inverse of the maximum absolute value of H to be used.
+C          HMXI = 0.0 is allowed and corresponds to an infinite HMAX.
+C HNEW   = The step size to be attempted on the next step.
+C HRL1   = Saved value of H*RL1.
+C HSCAL  = Stepsize in scaling of YH array.
+C PRL1   = The saved value of RL1.
+C RC     = Ratio of current H*RL1 to value on last ZVJAC call.
+C RL1    = The reciprocal of the coefficient EL(1).
+C SRUR   = Sqrt(UROUND), used in difference quotient algorithms.
+C TAU    = Real vector of past NQ step sizes, length 13.
+C TQ     = A real vector of length 5 in which ZVSET stores constants
+C          used for the convergence test, the error test, and the
+C          selection of H at a new order.
+C TN     = The independent variable, updated on each step taken.
+C UROUND = The machine unit roundoff.  The smallest positive real number
+C          such that  1.0 + UROUND .ne. 1.0
+C ICF    = Integer flag for convergence failure in ZVNLSD:
+C            0 means no failures.
+C            1 means convergence failure with out of date Jacobian
+C                   (recoverable error).
+C            2 means convergence failure with current Jacobian or
+C                   singular matrix (unrecoverable error).
+C INIT   = Saved integer flag indicating whether initialization of the
+C          problem has been done (INIT = 1) or not.
+C IPUP   = Saved flag to signal updating of Newton matrix.
+C JCUR   = Output flag from ZVJAC showing Jacobian status:
+C            JCUR = 0 means J is not current.
+C            JCUR = 1 means J is current.
+C JSTART = Integer flag used as input to ZVSTEP:
+C            0  means perform the first step.
+C            1  means take a new step continuing from the last.
+C            -1 means take the next step with a new value of MAXORD,
+C                  HMIN, HMXI, N, METH, MITER, and/or matrix parameters.
+C          On return, ZVSTEP sets JSTART = 1.
+C JSV    = Integer flag for Jacobian saving, = sign(MF).
+C KFLAG  = A completion code from ZVSTEP with the following meanings:
+C               0      the step was succesful.
+C              -1      the requested error could not be achieved.
+C              -2      corrector convergence could not be achieved.
+C              -3, -4  fatal error in VNLS (can not occur here).
+C KUTH   = Input flag to ZVSTEP showing whether H was reduced by the
+C          driver.  KUTH = 1 if H was reduced, = 0 otherwise.
+C L      = Integer variable, NQ + 1, current order plus one.
+C LMAX   = MAXORD + 1 (used for dimensioning).
+C LOCJS  = A pointer to the saved Jacobian, whose storage starts at
+C          WM(LOCJS), if JSV = 1.
+C LYH, LEWT, LACOR, LSAVF, LWM, LIWM = Saved integer pointers
+C          to segments of ZWORK, RWORK, and IWORK.
+C MAXORD = The maximum order of integration method to be allowed.
+C METH/MITER = The method flags.  See MF.
+C MSBJ   = The maximum number of steps between J evaluations, = 50.
+C MXHNIL = Saved value of optional input MXHNIL.
+C MXSTEP = Saved value of optional input MXSTEP.
+C N      = The number of first-order ODEs, = NEQ.
+C NEWH   = Saved integer to flag change of H.
+C NEWQ   = The method order to be used on the next step.
+C NHNIL  = Saved counter for occurrences of T + H = T.
+C NQ     = Integer variable, the current integration method order.
+C NQNYH  = Saved value of NQ*NYH.
+C NQWAIT = A counter controlling the frequency of order changes.
+C          An order change is about to be considered if NQWAIT = 1.
+C NSLJ   = The number of steps taken as of the last Jacobian update.
+C NSLP   = Saved value of NST as of last Newton matrix update.
+C NYH    = Saved value of the initial value of NEQ.
+C HU     = The step size in t last used.
+C NCFN   = Number of nonlinear convergence failures so far.
+C NETF   = The number of error test failures of the integrator so far.
+C NFE    = The number of f evaluations for the problem so far.
+C NJE    = The number of Jacobian evaluations so far.
+C NLU    = The number of matrix LU decompositions so far.
+C NNI    = Number of nonlinear iterations so far.
+C NQU    = The method order last used.
+C NST    = The number of steps taken for the problem so far.
+C-----------------------------------------------------------------------
+      COMMON /ZVOD01/ ACNRM, CCMXJ, CONP, CRATE, DRC, EL(13), ETA,
+     1                ETAMAX, H, HMIN, HMXI, HNEW, HRL1, HSCAL, PRL1,
+     2                RC, RL1, SRUR, TAU(13), TQ(5), TN, UROUND,
+     3                ICF, INIT, IPUP, JCUR, JSTART, JSV, KFLAG, KUTH,
+     4                L, LMAX, LYH, LEWT, LACOR, LSAVF, LWM, LIWM,
+     5                LOCJS, MAXORD, METH, MITER, MSBJ, MXHNIL, MXSTEP,
+     6                N, NEWH, NEWQ, NHNIL, NQ, NQNYH, NQWAIT, NSLJ,
+     7                NSLP, NYH
+      COMMON /ZVOD02/ HU, NCFN, NETF, NFE, NJE, NLU, NNI, NQU, NST
+C
+      DATA  MORD(1) /12/, MORD(2) /5/, MXSTP0 /500/, MXHNL0 /10/
+      DATA ZERO /0.0D0/, ONE /1.0D0/, TWO /2.0D0/, FOUR /4.0D0/,
+     1     PT2 /0.2D0/, HUN /100.0D0/
+C-----------------------------------------------------------------------
+C Block A.
+C This code block is executed on every call.
+C It tests ISTATE and ITASK for legality and branches appropriately.
+C If ISTATE .gt. 1 but the flag INIT shows that initialization has
+C not yet been done, an error return occurs.
+C If ISTATE = 1 and TOUT = T, return immediately.
+C-----------------------------------------------------------------------
+      IF (ISTATE .LT. 1 .OR. ISTATE .GT. 3) GO TO 601
+      IF (ITASK .LT. 1 .OR. ITASK .GT. 5) GO TO 602
+      IF (ISTATE .EQ. 1) GO TO 10
+      IF (INIT .NE. 1) GO TO 603
+      IF (ISTATE .EQ. 2) GO TO 200
+      GO TO 20
+ 10   INIT = 0
+      IF (TOUT .EQ. T) RETURN
+C-----------------------------------------------------------------------
+C Block B.
+C The next code block is executed for the initial call (ISTATE = 1),
+C or for a continuation call with parameter changes (ISTATE = 3).
+C It contains checking of all input and various initializations.
+C
+C First check legality of the non-optional input NEQ, ITOL, IOPT,
+C MF, ML, and MU.
+C-----------------------------------------------------------------------
+ 20   IF (NEQ .LE. 0) GO TO 604
+      IF (ISTATE .EQ. 1) GO TO 25
+      IF (NEQ .GT. N) GO TO 605
+ 25   N = NEQ
+      IF (ITOL .LT. 1 .OR. ITOL .GT. 4) GO TO 606
+      IF (IOPT .LT. 0 .OR. IOPT .GT. 1) GO TO 607
+      JSV = SIGN(1,MF)
+      MFA = ABS(MF)
+      METH = MFA/10
+      MITER = MFA - 10*METH
+      IF (METH .LT. 1 .OR. METH .GT. 2) GO TO 608
+      IF (MITER .LT. 0 .OR. MITER .GT. 5) GO TO 608
+      IF (MITER .LE. 3) GO TO 30
+      ML = IWORK(1)
+      MU = IWORK(2)
+      IF (ML .LT. 0 .OR. ML .GE. N) GO TO 609
+      IF (MU .LT. 0 .OR. MU .GE. N) GO TO 610
+ 30   CONTINUE
+C Next process and check the optional input. ---------------------------
+      IF (IOPT .EQ. 1) GO TO 40
+      MAXORD = MORD(METH)
+      MXSTEP = MXSTP0
+      MXHNIL = MXHNL0
+      IF (ISTATE .EQ. 1) H0 = ZERO
+      HMXI = ZERO
+      HMIN = ZERO
+      GO TO 60
+ 40   MAXORD = IWORK(5)
+      IF (MAXORD .LT. 0) GO TO 611
+      IF (MAXORD .EQ. 0) MAXORD = 100
+      MAXORD = MIN(MAXORD,MORD(METH))
+      MXSTEP = IWORK(6)
+      IF (MXSTEP .LT. 0) GO TO 612
+      IF (MXSTEP .EQ. 0) MXSTEP = MXSTP0
+      MXHNIL = IWORK(7)
+      IF (MXHNIL .LT. 0) GO TO 613
+      IF (MXHNIL .EQ. 0) MXHNIL = MXHNL0
+      IF (ISTATE .NE. 1) GO TO 50
+      H0 = RWORK(5)
+      IF ((TOUT - T)*H0 .LT. ZERO) GO TO 614
+ 50   HMAX = RWORK(6)
+      IF (HMAX .LT. ZERO) GO TO 615
+      HMXI = ZERO
+      IF (HMAX .GT. ZERO) HMXI = ONE/HMAX
+      HMIN = RWORK(7)
+      IF (HMIN .LT. ZERO) GO TO 616
+C-----------------------------------------------------------------------
+C Set work array pointers and check lengths LZW, LRW, and LIW.
+C Pointers to segments of ZWORK, RWORK, and IWORK are named by prefixing
+C L to the name of the segment.  E.g., segment YH starts at ZWORK(LYH).
+C Segments of ZWORK (in order) are denoted  YH, WM, SAVF, ACOR.
+C Besides optional inputs/outputs, RWORK has only the segment EWT.
+C Within WM, LOCJS is the location of the saved Jacobian (JSV .gt. 0).
+C-----------------------------------------------------------------------
+ 60   LYH = 1
+      IF (ISTATE .EQ. 1) NYH = N
+      LWM = LYH + (MAXORD + 1)*NYH
+      JCO = MAX(0,JSV)
+      IF (MITER .EQ. 0) LENWM = 0
+      IF (MITER .EQ. 1 .OR. MITER .EQ. 2) THEN
+        LENWM = (1 + JCO)*N*N
+        LOCJS = N*N + 1
+      ENDIF
+      IF (MITER .EQ. 3) LENWM = N
+      IF (MITER .EQ. 4 .OR. MITER .EQ. 5) THEN
+        MBAND = ML + MU + 1
+        LENP = (MBAND + ML)*N
+        LENJ = MBAND*N
+        LENWM = LENP + JCO*LENJ
+        LOCJS = LENP + 1
+        ENDIF
+      LSAVF = LWM + LENWM
+      LACOR = LSAVF + N
+      LENZW = LACOR + N - 1
+      IWORK(17) = LENZW
+      LEWT = 21
+      LENRW = 20 + N
+      IWORK(18) = LENRW
+      LIWM = 1
+      LENIW = 30 + N
+      IF (MITER .EQ. 0 .OR. MITER .EQ. 3) LENIW = 30
+      IWORK(19) = LENIW
+      IF (LENZW .GT. LZW) GO TO 628
+      IF (LENRW .GT. LRW) GO TO 617
+      IF (LENIW .GT. LIW) GO TO 618
+C Check RTOL and ATOL for legality. ------------------------------------
+      RTOLI = RTOL(1)
+      ATOLI = ATOL(1)
+      DO 70 I = 1,N
+        IF (ITOL .GE. 3) RTOLI = RTOL(I)
+        IF (ITOL .EQ. 2 .OR. ITOL .EQ. 4) ATOLI = ATOL(I)
+        IF (RTOLI .LT. ZERO) GO TO 619
+        IF (ATOLI .LT. ZERO) GO TO 620
+ 70     CONTINUE
+      IF (ISTATE .EQ. 1) GO TO 100
+C If ISTATE = 3, set flag to signal parameter changes to ZVSTEP. -------
+      JSTART = -1
+      IF (NQ .LE. MAXORD) GO TO 200
+C MAXORD was reduced below NQ.  Copy YH(*,MAXORD+2) into SAVF. ---------
+      CALL ZCOPY (N, ZWORK(LWM), 1, ZWORK(LSAVF), 1)
+      GO TO 200
+C-----------------------------------------------------------------------
+C Block C.
+C The next block is for the initial call only (ISTATE = 1).
+C It contains all remaining initializations, the initial call to F,
+C and the calculation of the initial step size.
+C The error weights in EWT are inverted after being loaded.
+C-----------------------------------------------------------------------
+ 100  UROUND = DUMACH()
+      TN = T
+      IF (ITASK .NE. 4 .AND. ITASK .NE. 5) GO TO 110
+      TCRIT = RWORK(1)
+      IF ((TCRIT - TOUT)*(TOUT - T) .LT. ZERO) GO TO 625
+      IF (H0 .NE. ZERO .AND. (T + H0 - TCRIT)*H0 .GT. ZERO)
+     1   H0 = TCRIT - T
+ 110  JSTART = 0
+      IF (MITER .GT. 0) SRUR = SQRT(UROUND)
+      CCMXJ = PT2
+      MSBJ = 50
+      NHNIL = 0
+      NST = 0
+      NJE = 0
+      NNI = 0
+      NCFN = 0
+      NETF = 0
+      NLU = 0
+      NSLJ = 0
+      NSLAST = 0
+      HU = ZERO
+      NQU = 0
+C Initial call to F.  (LF0 points to YH(*,2).) -------------------------
+      LF0 = LYH + NYH
+      CALL F (N, T, Y, ZWORK(LF0), RPAR, IPAR)
+      NFE = 1
+C Load the initial value vector in YH. ---------------------------------
+      CALL ZCOPY (N, Y, 1, ZWORK(LYH), 1)
+C Load and invert the EWT array.  (H is temporarily set to 1.0.) -------
+      NQ = 1
+      H = ONE
+      CALL ZEWSET (N, ITOL, RTOL, ATOL, ZWORK(LYH), RWORK(LEWT))
+      DO 120 I = 1,N
+        IF (RWORK(I+LEWT-1) .LE. ZERO) GO TO 621
+ 120    RWORK(I+LEWT-1) = ONE/RWORK(I+LEWT-1)
+      IF (H0 .NE. ZERO) GO TO 180
+C Call ZVHIN to set initial step size H0 to be attempted. --------------
+      CALL ZVHIN (N, T, ZWORK(LYH), ZWORK(LF0), F, RPAR, IPAR, TOUT,
+     1   UROUND, RWORK(LEWT), ITOL, ATOL, Y, ZWORK(LACOR), H0,
+     2   NITER, IER)
+      NFE = NFE + NITER
+      IF (IER .NE. 0) GO TO 622
+C Adjust H0 if necessary to meet HMAX bound. ---------------------------
+ 180  RH = ABS(H0)*HMXI
+      IF (RH .GT. ONE) H0 = H0/RH
+C Load H with H0 and scale YH(*,2) by H0. ------------------------------
+      H = H0
+      CALL DZSCAL (N, H0, ZWORK(LF0), 1)
+      GO TO 270
+C-----------------------------------------------------------------------
+C Block D.
+C The next code block is for continuation calls only (ISTATE = 2 or 3)
+C and is to check stop conditions before taking a step.
+C-----------------------------------------------------------------------
+ 200  NSLAST = NST
+      KUTH = 0
+      GO TO (210, 250, 220, 230, 240), ITASK
+ 210  IF ((TN - TOUT)*H .LT. ZERO) GO TO 250
+      CALL ZVINDY (TOUT, 0, ZWORK(LYH), NYH, Y, IFLAG)
+      IF (IFLAG .NE. 0) GO TO 627
+      T = TOUT
+      GO TO 420
+ 220  TP = TN - HU*(ONE + HUN*UROUND)
+      IF ((TP - TOUT)*H .GT. ZERO) GO TO 623
+      IF ((TN - TOUT)*H .LT. ZERO) GO TO 250
+      GO TO 400
+ 230  TCRIT = RWORK(1)
+      IF ((TN - TCRIT)*H .GT. ZERO) GO TO 624
+      IF ((TCRIT - TOUT)*H .LT. ZERO) GO TO 625
+      IF ((TN - TOUT)*H .LT. ZERO) GO TO 245
+      CALL ZVINDY (TOUT, 0, ZWORK(LYH), NYH, Y, IFLAG)
+      IF (IFLAG .NE. 0) GO TO 627
+      T = TOUT
+      GO TO 420
+ 240  TCRIT = RWORK(1)
+      IF ((TN - TCRIT)*H .GT. ZERO) GO TO 624
+ 245  HMX = ABS(TN) + ABS(H)
+      IHIT = ABS(TN - TCRIT) .LE. HUN*UROUND*HMX
+      IF (IHIT) GO TO 400
+      TNEXT = TN + HNEW*(ONE + FOUR*UROUND)
+      IF ((TNEXT - TCRIT)*H .LE. ZERO) GO TO 250
+      H = (TCRIT - TN)*(ONE - FOUR*UROUND)
+      KUTH = 1
+C-----------------------------------------------------------------------
+C Block E.
+C The next block is normally executed for all calls and contains
+C the call to the one-step core integrator ZVSTEP.
+C
+C This is a looping point for the integration steps.
+C
+C First check for too many steps being taken, update EWT (if not at
+C start of problem), check for too much accuracy being requested, and
+C check for H below the roundoff level in T.
+C-----------------------------------------------------------------------
+ 250  CONTINUE
+      IF ((NST-NSLAST) .GE. MXSTEP) GO TO 500
+      CALL ZEWSET (N, ITOL, RTOL, ATOL, ZWORK(LYH), RWORK(LEWT))
+      DO 260 I = 1,N
+        IF (RWORK(I+LEWT-1) .LE. ZERO) GO TO 510
+ 260    RWORK(I+LEWT-1) = ONE/RWORK(I+LEWT-1)
+ 270  TOLSF = UROUND*ZVNORM (N, ZWORK(LYH), RWORK(LEWT))
+      IF (TOLSF .LE. ONE) GO TO 280
+      TOLSF = TOLSF*TWO
+      IF (NST .EQ. 0) GO TO 626
+      GO TO 520
+ 280  IF ((TN + H) .NE. TN) GO TO 290
+      NHNIL = NHNIL + 1
+      IF (NHNIL .GT. MXHNIL) GO TO 290
+      MSG = 'ZVODE--  Warning: internal T (=R1) and H (=R2) are'
+      CALL XERRWD (MSG, 50, 101, 1, 0, 0, 0, 0, ZERO, ZERO)
+      MSG='      such that in the machine, T + H = T on the next step  '
+      CALL XERRWD (MSG, 60, 101, 1, 0, 0, 0, 0, ZERO, ZERO)
+      MSG = '      (H = step size). solver will continue anyway'
+      CALL XERRWD (MSG, 50, 101, 1, 0, 0, 0, 2, TN, H)
+      IF (NHNIL .LT. MXHNIL) GO TO 290
+      MSG = 'ZVODE--  Above warning has been issued I1 times.  '
+      CALL XERRWD (MSG, 50, 102, 1, 0, 0, 0, 0, ZERO, ZERO)
+      MSG = '      it will not be issued again for this problem'
+      CALL XERRWD (MSG, 50, 102, 1, 1, MXHNIL, 0, 0, ZERO, ZERO)
+ 290  CONTINUE
+C-----------------------------------------------------------------------
+C CALL ZVSTEP (Y, YH, NYH, YH, EWT, SAVF, VSAV, ACOR,
+C              WM, IWM, F, JAC, F, ZVNLSD, RPAR, IPAR)
+C-----------------------------------------------------------------------
+      CALL ZVSTEP (Y, ZWORK(LYH), NYH, ZWORK(LYH), RWORK(LEWT),
+     1   ZWORK(LSAVF), Y, ZWORK(LACOR), ZWORK(LWM), IWORK(LIWM),
+     2   F, JAC, F, ZVNLSD, RPAR, IPAR)
+      KGO = 1 - KFLAG
+C Branch on KFLAG.  Note: In this version, KFLAG can not be set to -3.
+C  KFLAG .eq. 0,   -1,  -2
+      GO TO (300, 530, 540), KGO
+C-----------------------------------------------------------------------
+C Block F.
+C The following block handles the case of a successful return from the
+C core integrator (KFLAG = 0).  Test for stop conditions.
+C-----------------------------------------------------------------------
+ 300  INIT = 1
+      KUTH = 0
+      GO TO (310, 400, 330, 340, 350), ITASK
+C ITASK = 1.  If TOUT has been reached, interpolate. -------------------
+ 310  IF ((TN - TOUT)*H .LT. ZERO) GO TO 250
+      CALL ZVINDY (TOUT, 0, ZWORK(LYH), NYH, Y, IFLAG)
+      T = TOUT
+      GO TO 420
+ 330  IF ((TN - TOUT)*H .GE. ZERO) GO TO 400
+      GO TO 250
+C ITASK = 4.  See if TOUT or TCRIT was reached.  Adjust H if necessary.
+ 340  IF ((TN - TOUT)*H .LT. ZERO) GO TO 345
+      CALL ZVINDY (TOUT, 0, ZWORK(LYH), NYH, Y, IFLAG)
+      T = TOUT
+      GO TO 420
+ 345  HMX = ABS(TN) + ABS(H)
+      IHIT = ABS(TN - TCRIT) .LE. HUN*UROUND*HMX
+      IF (IHIT) GO TO 400
+      TNEXT = TN + HNEW*(ONE + FOUR*UROUND)
+      IF ((TNEXT - TCRIT)*H .LE. ZERO) GO TO 250
+      H = (TCRIT - TN)*(ONE - FOUR*UROUND)
+      KUTH = 1
+      GO TO 250
+ 350  HMX = ABS(TN) + ABS(H)
+      IHIT = ABS(TN - TCRIT) .LE. HUN*UROUND*HMX
+C-----------------------------------------------------------------------
+C Block G.
+C The following block handles all successful returns from ZVODE.
+C If ITASK .ne. 1, Y is loaded from YH and T is set accordingly.
+C ISTATE is set to 2, and the optional output is loaded into the work
+C arrays before returning.
+C-----------------------------------------------------------------------
+ 400  CONTINUE
+      CALL ZCOPY (N, ZWORK(LYH), 1, Y, 1)
+      T = TN
+      IF (ITASK .NE. 4 .AND. ITASK .NE. 5) GO TO 420
+      IF (IHIT) T = TCRIT
+ 420  ISTATE = 2
+      RWORK(11) = HU
+      RWORK(12) = HNEW
+      RWORK(13) = TN
+      IWORK(11) = NST
+      IWORK(12) = NFE
+      IWORK(13) = NJE
+      IWORK(14) = NQU
+      IWORK(15) = NEWQ
+      IWORK(20) = NLU
+      IWORK(21) = NNI
+      IWORK(22) = NCFN
+      IWORK(23) = NETF
+      RETURN
+C-----------------------------------------------------------------------
+C Block H.
+C The following block handles all unsuccessful returns other than
+C those for illegal input.  First the error message routine is called.
+C if there was an error test or convergence test failure, IMXER is set.
+C Then Y is loaded from YH, and T is set to TN.
+C The optional output is loaded into the work arrays before returning.
+C-----------------------------------------------------------------------
+C The maximum number of steps was taken before reaching TOUT. ----------
+ 500  MSG = 'ZVODE--  At current T (=R1), MXSTEP (=I1) steps   '
+      CALL XERRWD (MSG, 50, 201, 1, 0, 0, 0, 0, ZERO, ZERO)
+      MSG = '      taken on this call before reaching TOUT     '
+      CALL XERRWD (MSG, 50, 201, 1, 1, MXSTEP, 0, 1, TN, ZERO)
+      ISTATE = -1
+      GO TO 580
+C EWT(i) .le. 0.0 for some i (not at start of problem). ----------------
+ 510  EWTI = RWORK(LEWT+I-1)
+      MSG = 'ZVODE--  At T (=R1), EWT(I1) has become R2 .le. 0.'
+      CALL XERRWD (MSG, 50, 202, 1, 1, I, 0, 2, TN, EWTI)
+      ISTATE = -6
+      GO TO 580
+C Too much accuracy requested for machine precision. -------------------
+ 520  MSG = 'ZVODE--  At T (=R1), too much accuracy requested  '
+      CALL XERRWD (MSG, 50, 203, 1, 0, 0, 0, 0, ZERO, ZERO)
+      MSG = '      for precision of machine:   see TOLSF (=R2) '
+      CALL XERRWD (MSG, 50, 203, 1, 0, 0, 0, 2, TN, TOLSF)
+      RWORK(14) = TOLSF
+      ISTATE = -2
+      GO TO 580
+C KFLAG = -1.  Error test failed repeatedly or with ABS(H) = HMIN. -----
+ 530  MSG = 'ZVODE--  At T(=R1) and step size H(=R2), the error'
+      CALL XERRWD (MSG, 50, 204, 1, 0, 0, 0, 0, ZERO, ZERO)
+      MSG = '      test failed repeatedly or with abs(H) = HMIN'
+      CALL XERRWD (MSG, 50, 204, 1, 0, 0, 0, 2, TN, H)
+      ISTATE = -4
+      GO TO 560
+C KFLAG = -2.  Convergence failed repeatedly or with ABS(H) = HMIN. ----
+ 540  MSG = 'ZVODE--  At T (=R1) and step size H (=R2), the    '
+      CALL XERRWD (MSG, 50, 205, 1, 0, 0, 0, 0, ZERO, ZERO)
+      MSG = '      corrector convergence failed repeatedly     '
+      CALL XERRWD (MSG, 50, 205, 1, 0, 0, 0, 0, ZERO, ZERO)
+      MSG = '      or with abs(H) = HMIN   '
+      CALL XERRWD (MSG, 30, 205, 1, 0, 0, 0, 2, TN, H)
+      ISTATE = -5
+C Compute IMXER if relevant. -------------------------------------------
+ 560  BIG = ZERO
+      IMXER = 1
+      DO 570 I = 1,N
+        SIZE = ABS(ZWORK(I+LACOR-1))*RWORK(I+LEWT-1)
+        IF (BIG .GE. SIZE) GO TO 570
+        BIG = SIZE
+        IMXER = I
+ 570    CONTINUE
+      IWORK(16) = IMXER
+C Set Y vector, T, and optional output. --------------------------------
+ 580  CONTINUE
+      CALL ZCOPY (N, ZWORK(LYH), 1, Y, 1)
+      T = TN
+      RWORK(11) = HU
+      RWORK(12) = H
+      RWORK(13) = TN
+      IWORK(11) = NST
+      IWORK(12) = NFE
+      IWORK(13) = NJE
+      IWORK(14) = NQU
+      IWORK(15) = NQ
+      IWORK(20) = NLU
+      IWORK(21) = NNI
+      IWORK(22) = NCFN
+      IWORK(23) = NETF
+      RETURN
+C-----------------------------------------------------------------------
+C Block I.
+C The following block handles all error returns due to illegal input
+C (ISTATE = -3), as detected before calling the core integrator.
+C First the error message routine is called.   If the illegal input
+C is a negative ISTATE, the run is aborted (apparent infinite loop).
+C-----------------------------------------------------------------------
+ 601  MSG = 'ZVODE--  ISTATE (=I1) illegal '
+      CALL XERRWD (MSG, 30, 1, 1, 1, ISTATE, 0, 0, ZERO, ZERO)
+      IF (ISTATE .LT. 0) GO TO 800
+      GO TO 700
+ 602  MSG = 'ZVODE--  ITASK (=I1) illegal  '
+      CALL XERRWD (MSG, 30, 2, 1, 1, ITASK, 0, 0, ZERO, ZERO)
+      GO TO 700
+ 603  MSG='ZVODE--  ISTATE (=I1) .gt. 1 but ZVODE not initialized      '
+      CALL XERRWD (MSG, 60, 3, 1, 1, ISTATE, 0, 0, ZERO, ZERO)
+      GO TO 700
+ 604  MSG = 'ZVODE--  NEQ (=I1) .lt. 1     '
+      CALL XERRWD (MSG, 30, 4, 1, 1, NEQ, 0, 0, ZERO, ZERO)
+      GO TO 700
+ 605  MSG = 'ZVODE--  ISTATE = 3 and NEQ increased (I1 to I2)  '
+      CALL XERRWD (MSG, 50, 5, 1, 2, N, NEQ, 0, ZERO, ZERO)
+      GO TO 700
+ 606  MSG = 'ZVODE--  ITOL (=I1) illegal   '
+      CALL XERRWD (MSG, 30, 6, 1, 1, ITOL, 0, 0, ZERO, ZERO)
+      GO TO 700
+ 607  MSG = 'ZVODE--  IOPT (=I1) illegal   '
+      CALL XERRWD (MSG, 30, 7, 1, 1, IOPT, 0, 0, ZERO, ZERO)
+      GO TO 700
+ 608  MSG = 'ZVODE--  MF (=I1) illegal     '
+      CALL XERRWD (MSG, 30, 8, 1, 1, MF, 0, 0, ZERO, ZERO)
+      GO TO 700
+ 609  MSG = 'ZVODE--  ML (=I1) illegal:  .lt.0 or .ge.NEQ (=I2)'
+      CALL XERRWD (MSG, 50, 9, 1, 2, ML, NEQ, 0, ZERO, ZERO)
+      GO TO 700
+ 610  MSG = 'ZVODE--  MU (=I1) illegal:  .lt.0 or .ge.NEQ (=I2)'
+      CALL XERRWD (MSG, 50, 10, 1, 2, MU, NEQ, 0, ZERO, ZERO)
+      GO TO 700
+ 611  MSG = 'ZVODE--  MAXORD (=I1) .lt. 0  '
+      CALL XERRWD (MSG, 30, 11, 1, 1, MAXORD, 0, 0, ZERO, ZERO)
+      GO TO 700
+ 612  MSG = 'ZVODE--  MXSTEP (=I1) .lt. 0  '
+      CALL XERRWD (MSG, 30, 12, 1, 1, MXSTEP, 0, 0, ZERO, ZERO)
+      GO TO 700
+ 613  MSG = 'ZVODE--  MXHNIL (=I1) .lt. 0  '
+      CALL XERRWD (MSG, 30, 13, 1, 1, MXHNIL, 0, 0, ZERO, ZERO)
+      GO TO 700
+ 614  MSG = 'ZVODE--  TOUT (=R1) behind T (=R2)      '
+      CALL XERRWD (MSG, 40, 14, 1, 0, 0, 0, 2, TOUT, T)
+      MSG = '      integration direction is given by H0 (=R1)  '
+      CALL XERRWD (MSG, 50, 14, 1, 0, 0, 0, 1, H0, ZERO)
+      GO TO 700
+ 615  MSG = 'ZVODE--  HMAX (=R1) .lt. 0.0  '
+      CALL XERRWD (MSG, 30, 15, 1, 0, 0, 0, 1, HMAX, ZERO)
+      GO TO 700
+ 616  MSG = 'ZVODE--  HMIN (=R1) .lt. 0.0  '
+      CALL XERRWD (MSG, 30, 16, 1, 0, 0, 0, 1, HMIN, ZERO)
+      GO TO 700
+ 617  CONTINUE
+      MSG='ZVODE--  RWORK length needed, LENRW (=I1), exceeds LRW (=I2)'
+      CALL XERRWD (MSG, 60, 17, 1, 2, LENRW, LRW, 0, ZERO, ZERO)
+      GO TO 700
+ 618  CONTINUE
+      MSG='ZVODE--  IWORK length needed, LENIW (=I1), exceeds LIW (=I2)'
+      CALL XERRWD (MSG, 60, 18, 1, 2, LENIW, LIW, 0, ZERO, ZERO)
+      GO TO 700
+ 619  MSG = 'ZVODE--  RTOL(I1) is R1 .lt. 0.0        '
+      CALL XERRWD (MSG, 40, 19, 1, 1, I, 0, 1, RTOLI, ZERO)
+      GO TO 700
+ 620  MSG = 'ZVODE--  ATOL(I1) is R1 .lt. 0.0        '
+      CALL XERRWD (MSG, 40, 20, 1, 1, I, 0, 1, ATOLI, ZERO)
+      GO TO 700
+ 621  EWTI = RWORK(LEWT+I-1)
+      MSG = 'ZVODE--  EWT(I1) is R1 .le. 0.0         '
+      CALL XERRWD (MSG, 40, 21, 1, 1, I, 0, 1, EWTI, ZERO)
+      GO TO 700
+ 622  CONTINUE
+      MSG='ZVODE--  TOUT (=R1) too close to T(=R2) to start integration'
+      CALL XERRWD (MSG, 60, 22, 1, 0, 0, 0, 2, TOUT, T)
+      GO TO 700
+ 623  CONTINUE
+      MSG='ZVODE--  ITASK = I1 and TOUT (=R1) behind TCUR - HU (= R2)  '
+      CALL XERRWD (MSG, 60, 23, 1, 1, ITASK, 0, 2, TOUT, TP)
+      GO TO 700
+ 624  CONTINUE
+      MSG='ZVODE--  ITASK = 4 or 5 and TCRIT (=R1) behind TCUR (=R2)   '
+      CALL XERRWD (MSG, 60, 24, 1, 0, 0, 0, 2, TCRIT, TN)
+      GO TO 700
+ 625  CONTINUE
+      MSG='ZVODE--  ITASK = 4 or 5 and TCRIT (=R1) behind TOUT (=R2)   '
+      CALL XERRWD (MSG, 60, 25, 1, 0, 0, 0, 2, TCRIT, TOUT)
+      GO TO 700
+ 626  MSG = 'ZVODE--  At start of problem, too much accuracy   '
+      CALL XERRWD (MSG, 50, 26, 1, 0, 0, 0, 0, ZERO, ZERO)
+      MSG='      requested for precision of machine:   see TOLSF (=R1) '
+      CALL XERRWD (MSG, 60, 26, 1, 0, 0, 0, 1, TOLSF, ZERO)
+      RWORK(14) = TOLSF
+      GO TO 700
+ 627  MSG='ZVODE--  Trouble from ZVINDY.  ITASK = I1, TOUT = R1.       '
+      CALL XERRWD (MSG, 60, 27, 1, 1, ITASK, 0, 1, TOUT, ZERO)
+      GO TO 700
+ 628  CONTINUE
+      MSG='ZVODE--  ZWORK length needed, LENZW (=I1), exceeds LZW (=I2)'
+      CALL XERRWD (MSG, 60, 17, 1, 2, LENZW, LZW, 0, ZERO, ZERO)
+C
+ 700  CONTINUE
+      ISTATE = -3
+      RETURN
+C
+ 800  MSG = 'ZVODE--  Run aborted:  apparent infinite loop     '
+      CALL XERRWD (MSG, 50, 303, 2, 0, 0, 0, 0, ZERO, ZERO)
+      RETURN
+C----------------------- End of Subroutine ZVODE -----------------------
+      END
+*DECK ZVHIN
+      SUBROUTINE ZVHIN (N, T0, Y0, YDOT, F, RPAR, IPAR, TOUT, UROUND,
+     1   EWT, ITOL, ATOL, Y, TEMP, H0, NITER, IER)
+      EXTERNAL F
+      DOUBLE COMPLEX Y0, YDOT, Y, TEMP
+      DOUBLE PRECISION T0, TOUT, UROUND, EWT, ATOL, H0
+      INTEGER N, IPAR, ITOL, NITER, IER
+      DIMENSION Y0(*), YDOT(*), EWT(*), ATOL(*), Y(*),
+     1   TEMP(*), RPAR(*), IPAR(*)
+C-----------------------------------------------------------------------
+C Call sequence input -- N, T0, Y0, YDOT, F, RPAR, IPAR, TOUT, UROUND,
+C                        EWT, ITOL, ATOL, Y, TEMP
+C Call sequence output -- H0, NITER, IER
+C COMMON block variables accessed -- None
+C
+C Subroutines called by ZVHIN:  F
+C Function routines called by ZVHIN: ZVNORM
+C-----------------------------------------------------------------------
+C This routine computes the step size, H0, to be attempted on the
+C first step, when the user has not supplied a value for this.
+C
+C First we check that TOUT - T0 differs significantly from zero.  Then
+C an iteration is done to approximate the initial second derivative
+C and this is used to define h from w.r.m.s.norm(h**2 * yddot / 2) = 1.
+C A bias factor of 1/2 is applied to the resulting h.
+C The sign of H0 is inferred from the initial values of TOUT and T0.
+C
+C Communication with ZVHIN is done with the following variables:
+C
+C N      = Size of ODE system, input.
+C T0     = Initial value of independent variable, input.
+C Y0     = Vector of initial conditions, input.
+C YDOT   = Vector of initial first derivatives, input.
+C F      = Name of subroutine for right-hand side f(t,y), input.
+C RPAR, IPAR = User's real/complex and integer work arrays.
+C TOUT   = First output value of independent variable
+C UROUND = Machine unit roundoff
+C EWT, ITOL, ATOL = Error weights and tolerance parameters
+C                   as described in the driver routine, input.
+C Y, TEMP = Work arrays of length N.
+C H0     = Step size to be attempted, output.
+C NITER  = Number of iterations (and of f evaluations) to compute H0,
+C          output.
+C IER    = The error flag, returned with the value
+C          IER = 0  if no trouble occurred, or
+C          IER = -1 if TOUT and T0 are considered too close to proceed.
+C-----------------------------------------------------------------------
+C
+C Type declarations for local variables --------------------------------
+C
+      DOUBLE PRECISION AFI, ATOLI, DELYI, H, HALF, HG, HLB, HNEW, HRAT,
+     1     HUB, HUN, PT1, T1, TDIST, TROUND, TWO, YDDNRM
+      INTEGER I, ITER
+C
+C Type declaration for function subroutines called ---------------------
+C
+      DOUBLE PRECISION ZVNORM
+C-----------------------------------------------------------------------
+C The following Fortran-77 declaration is to cause the values of the
+C listed (local) variables to be saved between calls to this integrator.
+C-----------------------------------------------------------------------
+      SAVE HALF, HUN, PT1, TWO
+      DATA HALF /0.5D0/, HUN /100.0D0/, PT1 /0.1D0/, TWO /2.0D0/
+C
+      NITER = 0
+      TDIST = ABS(TOUT - T0)
+      TROUND = UROUND*MAX(ABS(T0),ABS(TOUT))
+      IF (TDIST .LT. TWO*TROUND) GO TO 100
+C
+C Set a lower bound on h based on the roundoff level in T0 and TOUT. ---
+      HLB = HUN*TROUND
+C Set an upper bound on h based on TOUT-T0 and the initial Y and YDOT. -
+      HUB = PT1*TDIST
+      ATOLI = ATOL(1)
+      DO 10 I = 1, N
+        IF (ITOL .EQ. 2 .OR. ITOL .EQ. 4) ATOLI = ATOL(I)
+        DELYI = PT1*ABS(Y0(I)) + ATOLI
+        AFI = ABS(YDOT(I))
+        IF (AFI*HUB .GT. DELYI) HUB = DELYI/AFI
+ 10     CONTINUE
+C
+C Set initial guess for h as geometric mean of upper and lower bounds. -
+      ITER = 0
+      HG = SQRT(HLB*HUB)
+C If the bounds have crossed, exit with the mean value. ----------------
+      IF (HUB .LT. HLB) THEN
+        H0 = HG
+        GO TO 90
+      ENDIF
+C
+C Looping point for iteration. -----------------------------------------
+ 50   CONTINUE
+C Estimate the second derivative as a difference quotient in f. --------
+      H = SIGN (HG, TOUT - T0)
+      T1 = T0 + H
+      DO 60 I = 1, N
+ 60     Y(I) = Y0(I) + H*YDOT(I)
+      CALL F (N, T1, Y, TEMP, RPAR, IPAR)
+      DO 70 I = 1, N
+ 70     TEMP(I) = (TEMP(I) - YDOT(I))/H
+      YDDNRM = ZVNORM (N, TEMP, EWT)
+C Get the corresponding new value of h. --------------------------------
+      IF (YDDNRM*HUB*HUB .GT. TWO) THEN
+        HNEW = SQRT(TWO/YDDNRM)
+      ELSE
+        HNEW = SQRT(HG*HUB)
+      ENDIF
+      ITER = ITER + 1
+C-----------------------------------------------------------------------
+C Test the stopping conditions.
+C Stop if the new and previous h values differ by a factor of .lt. 2.
+C Stop if four iterations have been done.  Also, stop with previous h
+C if HNEW/HG .gt. 2 after first iteration, as this probably means that
+C the second derivative value is bad because of cancellation error.
+C-----------------------------------------------------------------------
+      IF (ITER .GE. 4) GO TO 80
+      HRAT = HNEW/HG
+      IF ( (HRAT .GT. HALF) .AND. (HRAT .LT. TWO) ) GO TO 80
+      IF ( (ITER .GE. 2) .AND. (HNEW .GT. TWO*HG) ) THEN
+        HNEW = HG
+        GO TO 80
+      ENDIF
+      HG = HNEW
+      GO TO 50
+C
+C Iteration done.  Apply bounds, bias factor, and sign.  Then exit. ----
+ 80   H0 = HNEW*HALF
+      IF (H0 .LT. HLB) H0 = HLB
+      IF (H0 .GT. HUB) H0 = HUB
+ 90   H0 = SIGN(H0, TOUT - T0)
+      NITER = ITER
+      IER = 0
+      RETURN
+C Error return for TOUT - T0 too small. --------------------------------
+ 100  IER = -1
+      RETURN
+C----------------------- End of Subroutine ZVHIN -----------------------
+      END
+*DECK ZVINDY
+      SUBROUTINE ZVINDY (T, K, YH, LDYH, DKY, IFLAG)
+      DOUBLE COMPLEX YH, DKY
+      DOUBLE PRECISION T
+      INTEGER K, LDYH, IFLAG
+      DIMENSION YH(LDYH,*), DKY(*)
+C-----------------------------------------------------------------------
+C Call sequence input -- T, K, YH, LDYH
+C Call sequence output -- DKY, IFLAG
+C COMMON block variables accessed:
+C     /ZVOD01/ --  H, TN, UROUND, L, N, NQ
+C     /ZVOD02/ --  HU
+C
+C Subroutines called by ZVINDY: DZSCAL, XERRWD
+C Function routines called by ZVINDY: None
+C-----------------------------------------------------------------------
+C ZVINDY computes interpolated values of the K-th derivative of the
+C dependent variable vector y, and stores it in DKY.  This routine
+C is called within the package with K = 0 and T = TOUT, but may
+C also be called by the user for any K up to the current order.
+C (See detailed instructions in the usage documentation.)
+C-----------------------------------------------------------------------
+C The computed values in DKY are gotten by interpolation using the
+C Nordsieck history array YH.  This array corresponds uniquely to a
+C vector-valued polynomial of degree NQCUR or less, and DKY is set
+C to the K-th derivative of this polynomial at T.
+C The formula for DKY is:
+C              q
+C  DKY(i)  =  sum  c(j,K) * (T - TN)**(j-K) * H**(-j) * YH(i,j+1)
+C             j=K
+C where  c(j,K) = j*(j-1)*...*(j-K+1), q = NQCUR, TN = TCUR, H = HCUR.
+C The quantities  NQ = NQCUR, L = NQ+1, N, TN, and H are
+C communicated by COMMON.  The above sum is done in reverse order.
+C IFLAG is returned negative if either K or T is out of bounds.
+C
+C Discussion above and comments in driver explain all variables.
+C-----------------------------------------------------------------------
+C
+C Type declarations for labeled COMMON block ZVOD01 --------------------
+C
+      DOUBLE PRECISION ACNRM, CCMXJ, CONP, CRATE, DRC, EL,
+     1     ETA, ETAMAX, H, HMIN, HMXI, HNEW, HRL1, HSCAL, PRL1,
+     2     RC, RL1, SRUR, TAU, TQ, TN, UROUND
+      INTEGER ICF, INIT, IPUP, JCUR, JSTART, JSV, KFLAG, KUTH,
+     1        L, LMAX, LYH, LEWT, LACOR, LSAVF, LWM, LIWM,
+     2        LOCJS, MAXORD, METH, MITER, MSBJ, MXHNIL, MXSTEP,
+     3        N, NEWH, NEWQ, NHNIL, NQ, NQNYH, NQWAIT, NSLJ,
+     4        NSLP, NYH
+C
+C Type declarations for labeled COMMON block ZVOD02 --------------------
+C
+      DOUBLE PRECISION HU
+      INTEGER NCFN, NETF, NFE, NJE, NLU, NNI, NQU, NST
+C
+C Type declarations for local variables --------------------------------
+C
+      DOUBLE PRECISION C, HUN, R, S, TFUZZ, TN1, TP, ZERO
+      INTEGER I, IC, J, JB, JB2, JJ, JJ1, JP1
+      CHARACTER*80 MSG
+C-----------------------------------------------------------------------
+C The following Fortran-77 declaration is to cause the values of the
+C listed (local) variables to be saved between calls to this integrator.
+C-----------------------------------------------------------------------
+      SAVE HUN, ZERO
+C
+      COMMON /ZVOD01/ ACNRM, CCMXJ, CONP, CRATE, DRC, EL(13), ETA,
+     1                ETAMAX, H, HMIN, HMXI, HNEW, HRL1, HSCAL, PRL1,
+     2                RC, RL1, SRUR, TAU(13), TQ(5), TN, UROUND,
+     3                ICF, INIT, IPUP, JCUR, JSTART, JSV, KFLAG, KUTH,
+     4                L, LMAX, LYH, LEWT, LACOR, LSAVF, LWM, LIWM,
+     5                LOCJS, MAXORD, METH, MITER, MSBJ, MXHNIL, MXSTEP,
+     6                N, NEWH, NEWQ, NHNIL, NQ, NQNYH, NQWAIT, NSLJ,
+     7                NSLP, NYH
+      COMMON /ZVOD02/ HU, NCFN, NETF, NFE, NJE, NLU, NNI, NQU, NST
+C
+      DATA HUN /100.0D0/, ZERO /0.0D0/
+C
+      IFLAG = 0
+      IF (K .LT. 0 .OR. K .GT. NQ) GO TO 80
+      TFUZZ = HUN*UROUND*SIGN(ABS(TN) + ABS(HU), HU)
+      TP = TN - HU - TFUZZ
+      TN1 = TN + TFUZZ
+      IF ((T-TP)*(T-TN1) .GT. ZERO) GO TO 90
+C
+      S = (T - TN)/H
+      IC = 1
+      IF (K .EQ. 0) GO TO 15
+      JJ1 = L - K
+      DO 10 JJ = JJ1, NQ
+ 10     IC = IC*JJ
+ 15   C = REAL(IC)
+      DO 20 I = 1, N
+ 20     DKY(I) = C*YH(I,L)
+      IF (K .EQ. NQ) GO TO 55
+      JB2 = NQ - K
+      DO 50 JB = 1, JB2
+        J = NQ - JB
+        JP1 = J + 1
+        IC = 1
+        IF (K .EQ. 0) GO TO 35
+        JJ1 = JP1 - K
+        DO 30 JJ = JJ1, J
+ 30       IC = IC*JJ
+ 35     C = REAL(IC)
+        DO 40 I = 1, N
+ 40       DKY(I) = C*YH(I,JP1) + S*DKY(I)
+ 50     CONTINUE
+      IF (K .EQ. 0) RETURN
+ 55   R = H**(-K)
+      CALL DZSCAL (N, R, DKY, 1)
+      RETURN
+C
+ 80   MSG = 'ZVINDY-- K (=I1) illegal      '
+      CALL XERRWD (MSG, 30, 51, 1, 1, K, 0, 0, ZERO, ZERO)
+      IFLAG = -1
+      RETURN
+ 90   MSG = 'ZVINDY-- T (=R1) illegal      '
+      CALL XERRWD (MSG, 30, 52, 1, 0, 0, 0, 1, T, ZERO)
+      MSG='      T not in interval TCUR - HU (= R1) to TCUR (=R2)      '
+      CALL XERRWD (MSG, 60, 52, 1, 0, 0, 0, 2, TP, TN)
+      IFLAG = -2
+      RETURN
+C----------------------- End of Subroutine ZVINDY ----------------------
+      END
+*DECK ZVSTEP
+      SUBROUTINE ZVSTEP (Y, YH, LDYH, YH1, EWT, SAVF, VSAV, ACOR,
+     1                  WM, IWM, F, JAC, PSOL, VNLS, RPAR, IPAR)
+      EXTERNAL F, JAC, PSOL, VNLS
+      DOUBLE COMPLEX Y, YH, YH1, SAVF, VSAV, ACOR, WM
+      DOUBLE PRECISION EWT
+      INTEGER LDYH, IWM, IPAR
+      DIMENSION Y(*), YH(LDYH,*), YH1(*), EWT(*), SAVF(*), VSAV(*),
+     1   ACOR(*), WM(*), IWM(*), RPAR(*), IPAR(*)
+C-----------------------------------------------------------------------
+C Call sequence input -- Y, YH, LDYH, YH1, EWT, SAVF, VSAV,
+C                        ACOR, WM, IWM, F, JAC, PSOL, VNLS, RPAR, IPAR
+C Call sequence output -- YH, ACOR, WM, IWM
+C COMMON block variables accessed:
+C     /ZVOD01/  ACNRM, EL(13), H, HMIN, HMXI, HNEW, HSCAL, RC, TAU(13),
+C               TQ(5), TN, JCUR, JSTART, KFLAG, KUTH,
+C               L, LMAX, MAXORD, N, NEWQ, NQ, NQWAIT
+C     /ZVOD02/  HU, NCFN, NETF, NFE, NQU, NST
+C
+C Subroutines called by ZVSTEP: F, DZAXPY, ZCOPY, DZSCAL,
+C                               ZVJUST, VNLS, ZVSET
+C Function routines called by ZVSTEP: ZVNORM
+C-----------------------------------------------------------------------
+C ZVSTEP performs one step of the integration of an initial value
+C problem for a system of ordinary differential equations.
+C ZVSTEP calls subroutine VNLS for the solution of the nonlinear system
+C arising in the time step.  Thus it is independent of the problem
+C Jacobian structure and the type of nonlinear system solution method.
+C ZVSTEP returns a completion flag KFLAG (in COMMON).
+C A return with KFLAG = -1 or -2 means either ABS(H) = HMIN or 10
+C consecutive failures occurred.  On a return with KFLAG negative,
+C the values of TN and the YH array are as of the beginning of the last
+C step, and H is the last step size attempted.
+C
+C Communication with ZVSTEP is done with the following variables:
+C
+C Y      = An array of length N used for the dependent variable vector.
+C YH     = An LDYH by LMAX array containing the dependent variables
+C          and their approximate scaled derivatives, where
+C          LMAX = MAXORD + 1.  YH(i,j+1) contains the approximate
+C          j-th derivative of y(i), scaled by H**j/factorial(j)
+C          (j = 0,1,...,NQ).  On entry for the first step, the first
+C          two columns of YH must be set from the initial values.
+C LDYH   = A constant integer .ge. N, the first dimension of YH.
+C          N is the number of ODEs in the system.
+C YH1    = A one-dimensional array occupying the same space as YH.
+C EWT    = An array of length N containing multiplicative weights
+C          for local error measurements.  Local errors in y(i) are
+C          compared to 1.0/EWT(i) in various error tests.
+C SAVF   = An array of working storage, of length N.
+C          also used for input of YH(*,MAXORD+2) when JSTART = -1
+C          and MAXORD .lt. the current order NQ.
+C VSAV   = A work array of length N passed to subroutine VNLS.
+C ACOR   = A work array of length N, used for the accumulated
+C          corrections.  On a successful return, ACOR(i) contains
+C          the estimated one-step local error in y(i).
+C WM,IWM = Complex and integer work arrays associated with matrix
+C          operations in VNLS.
+C F      = Dummy name for the user-supplied subroutine for f.
+C JAC    = Dummy name for the user-supplied Jacobian subroutine.
+C PSOL   = Dummy name for the subroutine passed to VNLS, for
+C          possible use there.
+C VNLS   = Dummy name for the nonlinear system solving subroutine,
+C          whose real name is dependent on the method used.
+C RPAR, IPAR = User's real/complex and integer work arrays.
+C-----------------------------------------------------------------------
+C
+C Type declarations for labeled COMMON block ZVOD01 --------------------
+C
+      DOUBLE PRECISION ACNRM, CCMXJ, CONP, CRATE, DRC, EL,
+     1     ETA, ETAMAX, H, HMIN, HMXI, HNEW, HRL1, HSCAL, PRL1,
+     2     RC, RL1, SRUR, TAU, TQ, TN, UROUND
+      INTEGER ICF, INIT, IPUP, JCUR, JSTART, JSV, KFLAG, KUTH,
+     1        L, LMAX, LYH, LEWT, LACOR, LSAVF, LWM, LIWM,
+     2        LOCJS, MAXORD, METH, MITER, MSBJ, MXHNIL, MXSTEP,
+     3        N, NEWH, NEWQ, NHNIL, NQ, NQNYH, NQWAIT, NSLJ,
+     4        NSLP, NYH
+C
+C Type declarations for labeled COMMON block ZVOD02 --------------------
+C
+      DOUBLE PRECISION HU
+      INTEGER NCFN, NETF, NFE, NJE, NLU, NNI, NQU, NST
+C
+C Type declarations for local variables --------------------------------
+C
+      DOUBLE PRECISION ADDON, BIAS1,BIAS2,BIAS3, CNQUOT, DDN, DSM, DUP,
+     1     ETACF, ETAMIN, ETAMX1, ETAMX2, ETAMX3, ETAMXF,
+     2     ETAQ, ETAQM1, ETAQP1, FLOTL, ONE, ONEPSM,
+     3     R, THRESH, TOLD, ZERO
+      INTEGER I, I1, I2, IBACK, J, JB, KFC, KFH, MXNCF, NCF, NFLAG
+C
+C Type declaration for function subroutines called ---------------------
+C
+      DOUBLE PRECISION ZVNORM
+C-----------------------------------------------------------------------
+C The following Fortran-77 declaration is to cause the values of the
+C listed (local) variables to be saved between calls to this integrator.
+C-----------------------------------------------------------------------
+      SAVE ADDON, BIAS1, BIAS2, BIAS3,
+     1     ETACF, ETAMIN, ETAMX1, ETAMX2, ETAMX3, ETAMXF, ETAQ, ETAQM1,
+     2     KFC, KFH, MXNCF, ONEPSM, THRESH, ONE, ZERO
+C-----------------------------------------------------------------------
+      COMMON /ZVOD01/ ACNRM, CCMXJ, CONP, CRATE, DRC, EL(13), ETA,
+     1                ETAMAX, H, HMIN, HMXI, HNEW, HRL1, HSCAL, PRL1,
+     2                RC, RL1, SRUR, TAU(13), TQ(5), TN, UROUND,
+     3                ICF, INIT, IPUP, JCUR, JSTART, JSV, KFLAG, KUTH,
+     4                L, LMAX, LYH, LEWT, LACOR, LSAVF, LWM, LIWM,
+     5                LOCJS, MAXORD, METH, MITER, MSBJ, MXHNIL, MXSTEP,
+     6                N, NEWH, NEWQ, NHNIL, NQ, NQNYH, NQWAIT, NSLJ,
+     7                NSLP, NYH
+      COMMON /ZVOD02/ HU, NCFN, NETF, NFE, NJE, NLU, NNI, NQU, NST
+C
+      DATA KFC/-3/, KFH/-7/, MXNCF/10/
+      DATA ADDON  /1.0D-6/,    BIAS1  /6.0D0/,     BIAS2  /6.0D0/,
+     1     BIAS3  /10.0D0/,    ETACF  /0.25D0/,    ETAMIN /0.1D0/,
+     2     ETAMXF /0.2D0/,     ETAMX1 /1.0D4/,     ETAMX2 /10.0D0/,
+     3     ETAMX3 /10.0D0/,    ONEPSM /1.00001D0/, THRESH /1.5D0/
+      DATA ONE/1.0D0/, ZERO/0.0D0/
+C
+      KFLAG = 0
+      TOLD = TN
+      NCF = 0
+      JCUR = 0
+      NFLAG = 0
+      IF (JSTART .GT. 0) GO TO 20
+      IF (JSTART .EQ. -1) GO TO 100
+C-----------------------------------------------------------------------
+C On the first call, the order is set to 1, and other variables are
+C initialized.  ETAMAX is the maximum ratio by which H can be increased
+C in a single step.  It is normally 10, but is larger during the
+C first step to compensate for the small initial H.  If a failure
+C occurs (in corrector convergence or error test), ETAMAX is set to 1
+C for the next increase.
+C-----------------------------------------------------------------------
+      LMAX = MAXORD + 1
+      NQ = 1
+      L = 2
+      NQNYH = NQ*LDYH
+      TAU(1) = H
+      PRL1 = ONE
+      RC = ZERO
+      ETAMAX = ETAMX1
+      NQWAIT = 2
+      HSCAL = H
+      GO TO 200
+C-----------------------------------------------------------------------
+C Take preliminary actions on a normal continuation step (JSTART.GT.0).
+C If the driver changed H, then ETA must be reset and NEWH set to 1.
+C If a change of order was dictated on the previous step, then
+C it is done here and appropriate adjustments in the history are made.
+C On an order decrease, the history array is adjusted by ZVJUST.
+C On an order increase, the history array is augmented by a column.
+C On a change of step size H, the history array YH is rescaled.
+C-----------------------------------------------------------------------
+ 20   CONTINUE
+      IF (KUTH .EQ. 1) THEN
+        ETA = MIN(ETA,H/HSCAL)
+        NEWH = 1
+        ENDIF
+ 50   IF (NEWH .EQ. 0) GO TO 200
+      IF (NEWQ .EQ. NQ) GO TO 150
+      IF (NEWQ .LT. NQ) THEN
+        CALL ZVJUST (YH, LDYH, -1)
+        NQ = NEWQ
+        L = NQ + 1
+        NQWAIT = L
+        GO TO 150
+        ENDIF
+      IF (NEWQ .GT. NQ) THEN
+        CALL ZVJUST (YH, LDYH, 1)
+        NQ = NEWQ
+        L = NQ + 1
+        NQWAIT = L
+        GO TO 150
+      ENDIF
+C-----------------------------------------------------------------------
+C The following block handles preliminaries needed when JSTART = -1.
+C If N was reduced, zero out part of YH to avoid undefined references.
+C If MAXORD was reduced to a value less than the tentative order NEWQ,
+C then NQ is set to MAXORD, and a new H ratio ETA is chosen.
+C Otherwise, we take the same preliminary actions as for JSTART .gt. 0.
+C In any case, NQWAIT is reset to L = NQ + 1 to prevent further
+C changes in order for that many steps.
+C The new H ratio ETA is limited by the input H if KUTH = 1,
+C by HMIN if KUTH = 0, and by HMXI in any case.
+C Finally, the history array YH is rescaled.
+C-----------------------------------------------------------------------
+ 100  CONTINUE
+      LMAX = MAXORD + 1
+      IF (N .EQ. LDYH) GO TO 120
+      I1 = 1 + (NEWQ + 1)*LDYH
+      I2 = (MAXORD + 1)*LDYH
+      IF (I1 .GT. I2) GO TO 120
+      DO 110 I = I1, I2
+ 110    YH1(I) = ZERO
+ 120  IF (NEWQ .LE. MAXORD) GO TO 140
+      FLOTL = REAL(LMAX)
+      IF (MAXORD .LT. NQ-1) THEN
+        DDN = ZVNORM (N, SAVF, EWT)/TQ(1)
+        ETA = ONE/((BIAS1*DDN)**(ONE/FLOTL) + ADDON)
+        ENDIF
+      IF (MAXORD .EQ. NQ .AND. NEWQ .EQ. NQ+1) ETA = ETAQ
+      IF (MAXORD .EQ. NQ-1 .AND. NEWQ .EQ. NQ+1) THEN
+        ETA = ETAQM1
+        CALL ZVJUST (YH, LDYH, -1)
+        ENDIF
+      IF (MAXORD .EQ. NQ-1 .AND. NEWQ .EQ. NQ) THEN
+        DDN = ZVNORM (N, SAVF, EWT)/TQ(1)
+        ETA = ONE/((BIAS1*DDN)**(ONE/FLOTL) + ADDON)
+        CALL ZVJUST (YH, LDYH, -1)
+        ENDIF
+      ETA = MIN(ETA,ONE)
+      NQ = MAXORD
+      L = LMAX
+ 140  IF (KUTH .EQ. 1) ETA = MIN(ETA,ABS(H/HSCAL))
+      IF (KUTH .EQ. 0) ETA = MAX(ETA,HMIN/ABS(HSCAL))
+      ETA = ETA/MAX(ONE,ABS(HSCAL)*HMXI*ETA)
+      NEWH = 1
+      NQWAIT = L
+      IF (NEWQ .LE. MAXORD) GO TO 50
+C Rescale the history array for a change in H by a factor of ETA. ------
+ 150  R = ONE
+      DO 180 J = 2, L
+        R = R*ETA
+        CALL DZSCAL (N, R, YH(1,J), 1 )
+ 180    CONTINUE
+      H = HSCAL*ETA
+      HSCAL = H
+      RC = RC*ETA
+      NQNYH = NQ*LDYH
+C-----------------------------------------------------------------------
+C This section computes the predicted values by effectively
+C multiplying the YH array by the Pascal triangle matrix.
+C ZVSET is called to calculate all integration coefficients.
+C RC is the ratio of new to old values of the coefficient H/EL(2)=h/l1.
+C-----------------------------------------------------------------------
+ 200  TN = TN + H
+      I1 = NQNYH + 1
+      DO 220 JB = 1, NQ
+        I1 = I1 - LDYH
+        DO 210 I = I1, NQNYH
+ 210      YH1(I) = YH1(I) + YH1(I+LDYH)
+ 220  CONTINUE
+      CALL ZVSET
+      RL1 = ONE/EL(2)
+      RC = RC*(RL1/PRL1)
+      PRL1 = RL1
+C
+C Call the nonlinear system solver. ------------------------------------
+C
+      CALL VNLS (Y, YH, LDYH, VSAV, SAVF, EWT, ACOR, IWM, WM,
+     1           F, JAC, PSOL, NFLAG, RPAR, IPAR)
+C
+      IF (NFLAG .EQ. 0) GO TO 450
+C-----------------------------------------------------------------------
+C The VNLS routine failed to achieve convergence (NFLAG .NE. 0).
+C The YH array is retracted to its values before prediction.
+C The step size H is reduced and the step is retried, if possible.
+C Otherwise, an error exit is taken.
+C-----------------------------------------------------------------------
+        NCF = NCF + 1
+        NCFN = NCFN + 1
+        ETAMAX = ONE
+        TN = TOLD
+        I1 = NQNYH + 1
+        DO 430 JB = 1, NQ
+          I1 = I1 - LDYH
+          DO 420 I = I1, NQNYH
+ 420        YH1(I) = YH1(I) - YH1(I+LDYH)
+ 430      CONTINUE
+        IF (NFLAG .LT. -1) GO TO 680
+        IF (ABS(H) .LE. HMIN*ONEPSM) GO TO 670
+        IF (NCF .EQ. MXNCF) GO TO 670
+        ETA = ETACF
+        ETA = MAX(ETA,HMIN/ABS(H))
+        NFLAG = -1
+        GO TO 150
+C-----------------------------------------------------------------------
+C The corrector has converged (NFLAG = 0).  The local error test is
+C made and control passes to statement 500 if it fails.
+C-----------------------------------------------------------------------
+ 450  CONTINUE
+      DSM = ACNRM/TQ(2)
+      IF (DSM .GT. ONE) GO TO 500
+C-----------------------------------------------------------------------
+C After a successful step, update the YH and TAU arrays and decrement
+C NQWAIT.  If NQWAIT is then 1 and NQ .lt. MAXORD, then ACOR is saved
+C for use in a possible order increase on the next step.
+C If ETAMAX = 1 (a failure occurred this step), keep NQWAIT .ge. 2.
+C-----------------------------------------------------------------------
+      KFLAG = 0
+      NST = NST + 1
+      HU = H
+      NQU = NQ
+      DO 470 IBACK = 1, NQ
+        I = L - IBACK
+ 470    TAU(I+1) = TAU(I)
+      TAU(1) = H
+      DO 480 J = 1, L
+        CALL DZAXPY (N, EL(J), ACOR, 1, YH(1,J), 1 )
+ 480    CONTINUE
+      NQWAIT = NQWAIT - 1
+      IF ((L .EQ. LMAX) .OR. (NQWAIT .NE. 1)) GO TO 490
+      CALL ZCOPY (N, ACOR, 1, YH(1,LMAX), 1 )
+      CONP = TQ(5)
+ 490  IF (ETAMAX .NE. ONE) GO TO 560
+      IF (NQWAIT .LT. 2) NQWAIT = 2
+      NEWQ = NQ
+      NEWH = 0
+      ETA = ONE
+      HNEW = H
+      GO TO 690
+C-----------------------------------------------------------------------
+C The error test failed.  KFLAG keeps track of multiple failures.
+C Restore TN and the YH array to their previous values, and prepare
+C to try the step again.  Compute the optimum step size for the
+C same order.  After repeated failures, H is forced to decrease
+C more rapidly.
+C-----------------------------------------------------------------------
+ 500  KFLAG = KFLAG - 1
+      NETF = NETF + 1
+      NFLAG = -2
+      TN = TOLD
+      I1 = NQNYH + 1
+      DO 520 JB = 1, NQ
+        I1 = I1 - LDYH
+        DO 510 I = I1, NQNYH
+ 510      YH1(I) = YH1(I) - YH1(I+LDYH)
+ 520  CONTINUE
+      IF (ABS(H) .LE. HMIN*ONEPSM) GO TO 660
+      ETAMAX = ONE
+      IF (KFLAG .LE. KFC) GO TO 530
+C Compute ratio of new H to current H at the current order. ------------
+      FLOTL = REAL(L)
+      ETA = ONE/((BIAS2*DSM)**(ONE/FLOTL) + ADDON)
+      ETA = MAX(ETA,HMIN/ABS(H),ETAMIN)
+      IF ((KFLAG .LE. -2) .AND. (ETA .GT. ETAMXF)) ETA = ETAMXF
+      GO TO 150
+C-----------------------------------------------------------------------
+C Control reaches this section if 3 or more consecutive failures
+C have occurred.  It is assumed that the elements of the YH array
+C have accumulated errors of the wrong order.  The order is reduced
+C by one, if possible.  Then H is reduced by a factor of 0.1 and
+C the step is retried.  After a total of 7 consecutive failures,
+C an exit is taken with KFLAG = -1.
+C-----------------------------------------------------------------------
+ 530  IF (KFLAG .EQ. KFH) GO TO 660
+      IF (NQ .EQ. 1) GO TO 540
+      ETA = MAX(ETAMIN,HMIN/ABS(H))
+      CALL ZVJUST (YH, LDYH, -1)
+      L = NQ
+      NQ = NQ - 1
+      NQWAIT = L
+      GO TO 150
+ 540  ETA = MAX(ETAMIN,HMIN/ABS(H))
+      H = H*ETA
+      HSCAL = H
+      TAU(1) = H
+      CALL F (N, TN, Y, SAVF, RPAR, IPAR)
+      NFE = NFE + 1
+      DO 550 I = 1, N
+ 550    YH(I,2) = H*SAVF(I)
+      NQWAIT = 10
+      GO TO 200
+C-----------------------------------------------------------------------
+C If NQWAIT = 0, an increase or decrease in order by one is considered.
+C Factors ETAQ, ETAQM1, ETAQP1 are computed by which H could
+C be multiplied at order q, q-1, or q+1, respectively.
+C The largest of these is determined, and the new order and
+C step size set accordingly.
+C A change of H or NQ is made only if H increases by at least a
+C factor of THRESH.  If an order change is considered and rejected,
+C then NQWAIT is set to 2 (reconsider it after 2 steps).
+C-----------------------------------------------------------------------
+C Compute ratio of new H to current H at the current order. ------------
+ 560  FLOTL = REAL(L)
+      ETAQ = ONE/((BIAS2*DSM)**(ONE/FLOTL) + ADDON)
+      IF (NQWAIT .NE. 0) GO TO 600
+      NQWAIT = 2
+      ETAQM1 = ZERO
+      IF (NQ .EQ. 1) GO TO 570
+C Compute ratio of new H to current H at the current order less one. ---
+      DDN = ZVNORM (N, YH(1,L), EWT)/TQ(1)
+      ETAQM1 = ONE/((BIAS1*DDN)**(ONE/(FLOTL - ONE)) + ADDON)
+ 570  ETAQP1 = ZERO
+      IF (L .EQ. LMAX) GO TO 580
+C Compute ratio of new H to current H at current order plus one. -------
+      CNQUOT = (TQ(5)/CONP)*(H/TAU(2))**L
+      DO 575 I = 1, N
+ 575    SAVF(I) = ACOR(I) - CNQUOT*YH(I,LMAX)
+      DUP = ZVNORM (N, SAVF, EWT)/TQ(3)
+      ETAQP1 = ONE/((BIAS3*DUP)**(ONE/(FLOTL + ONE)) + ADDON)
+ 580  IF (ETAQ .GE. ETAQP1) GO TO 590
+      IF (ETAQP1 .GT. ETAQM1) GO TO 620
+      GO TO 610
+ 590  IF (ETAQ .LT. ETAQM1) GO TO 610
+ 600  ETA = ETAQ
+      NEWQ = NQ
+      GO TO 630
+ 610  ETA = ETAQM1
+      NEWQ = NQ - 1
+      GO TO 630
+ 620  ETA = ETAQP1
+      NEWQ = NQ + 1
+      CALL ZCOPY (N, ACOR, 1, YH(1,LMAX), 1)
+C Test tentative new H against THRESH, ETAMAX, and HMXI, then exit. ----
+ 630  IF (ETA .LT. THRESH .OR. ETAMAX .EQ. ONE) GO TO 640
+      ETA = MIN(ETA,ETAMAX)
+      ETA = ETA/MAX(ONE,ABS(H)*HMXI*ETA)
+      NEWH = 1
+      HNEW = H*ETA
+      GO TO 690
+ 640  NEWQ = NQ
+      NEWH = 0
+      ETA = ONE
+      HNEW = H
+      GO TO 690
+C-----------------------------------------------------------------------
+C All returns are made through this section.
+C On a successful return, ETAMAX is reset and ACOR is scaled.
+C-----------------------------------------------------------------------
+ 660  KFLAG = -1
+      GO TO 720
+ 670  KFLAG = -2
+      GO TO 720
+ 680  IF (NFLAG .EQ. -2) KFLAG = -3
+      IF (NFLAG .EQ. -3) KFLAG = -4
+      GO TO 720
+ 690  ETAMAX = ETAMX3
+      IF (NST .LE. 10) ETAMAX = ETAMX2
+ 700  R = ONE/TQ(2)
+      CALL DZSCAL (N, R, ACOR, 1)
+ 720  JSTART = 1
+      RETURN
+C----------------------- End of Subroutine ZVSTEP ----------------------
+      END
+*DECK ZVSET
+      SUBROUTINE ZVSET
+C-----------------------------------------------------------------------
+C Call sequence communication: None
+C COMMON block variables accessed:
+C     /ZVOD01/ -- EL(13), H, TAU(13), TQ(5), L(= NQ + 1),
+C                 METH, NQ, NQWAIT
+C
+C Subroutines called by ZVSET: None
+C Function routines called by ZVSET: None
+C-----------------------------------------------------------------------
+C ZVSET is called by ZVSTEP and sets coefficients for use there.
+C
+C For each order NQ, the coefficients in EL are calculated by use of
+C  the generating polynomial lambda(x), with coefficients EL(i).
+C      lambda(x) = EL(1) + EL(2)*x + ... + EL(NQ+1)*(x**NQ).
+C For the backward differentiation formulas,
+C                                     NQ-1
+C      lambda(x) = (1 + x/xi*(NQ)) * product (1 + x/xi(i) ) .
+C                                     i = 1
+C                              NQ-1
+C      (d/dx) lambda(x) = c * product (1 + x/xi(i) ) ,
+C                              i = 1
+C      lambda(-1) = 0,    lambda(0) = 1,
+C where c is a normalization constant.
+C In both cases, xi(i) is defined by
+C      H*xi(i) = t sub n  -  t sub (n-i)
+C              = H + TAU(1) + TAU(2) + ... TAU(i-1).
+C
+C
+C In addition to variables described previously, communication
+C with ZVSET uses the following:
+C   TAU    = A vector of length 13 containing the past NQ values
+C            of H.
+C   EL     = A vector of length 13 in which vset stores the
+C            coefficients for the corrector formula.
+C   TQ     = A vector of length 5 in which vset stores constants
+C            used for the convergence test, the error test, and the
+C            selection of H at a new order.
+C   METH   = The basic method indicator.
+C   NQ     = The current order.
+C   L      = NQ + 1, the length of the vector stored in EL, and
+C            the number of columns of the YH array being used.
+C   NQWAIT = A counter controlling the frequency of order changes.
+C            An order change is about to be considered if NQWAIT = 1.
+C-----------------------------------------------------------------------
+C
+C Type declarations for labeled COMMON block ZVOD01 --------------------
+C
+      DOUBLE PRECISION ACNRM, CCMXJ, CONP, CRATE, DRC, EL,
+     1     ETA, ETAMAX, H, HMIN, HMXI, HNEW, HRL1, HSCAL, PRL1,
+     2     RC, RL1, SRUR, TAU, TQ, TN, UROUND
+      INTEGER ICF, INIT, IPUP, JCUR, JSTART, JSV, KFLAG, KUTH,
+     1        L, LMAX, LYH, LEWT, LACOR, LSAVF, LWM, LIWM,
+     2        LOCJS, MAXORD, METH, MITER, MSBJ, MXHNIL, MXSTEP,
+     3        N, NEWH, NEWQ, NHNIL, NQ, NQNYH, NQWAIT, NSLJ,
+     4        NSLP, NYH
+C
+C Type declarations for local variables --------------------------------
+C
+      DOUBLE PRECISION AHATN0, ALPH0, CNQM1, CORTES, CSUM, ELP, EM,
+     1     EM0, FLOTI, FLOTL, FLOTNQ, HSUM, ONE, RXI, RXIS, S, SIX,
+     2     T1, T2, T3, T4, T5, T6, TWO, XI, ZERO
+      INTEGER I, IBACK, J, JP1, NQM1, NQM2
+C
+      DIMENSION EM(13)
+C-----------------------------------------------------------------------
+C The following Fortran-77 declaration is to cause the values of the
+C listed (local) variables to be saved between calls to this integrator.
+C-----------------------------------------------------------------------
+      SAVE CORTES, ONE, SIX, TWO, ZERO
+C
+      COMMON /ZVOD01/ ACNRM, CCMXJ, CONP, CRATE, DRC, EL(13), ETA,
+     1                ETAMAX, H, HMIN, HMXI, HNEW, HRL1, HSCAL, PRL1,
+     2                RC, RL1, SRUR, TAU(13), TQ(5), TN, UROUND,
+     3                ICF, INIT, IPUP, JCUR, JSTART, JSV, KFLAG, KUTH,
+     4                L, LMAX, LYH, LEWT, LACOR, LSAVF, LWM, LIWM,
+     5                LOCJS, MAXORD, METH, MITER, MSBJ, MXHNIL, MXSTEP,
+     6                N, NEWH, NEWQ, NHNIL, NQ, NQNYH, NQWAIT, NSLJ,
+     7                NSLP, NYH
+C
+      DATA CORTES /0.1D0/
+      DATA ONE  /1.0D0/, SIX /6.0D0/, TWO /2.0D0/, ZERO /0.0D0/
+C
+      FLOTL = REAL(L)
+      NQM1 = NQ - 1
+      NQM2 = NQ - 2
+      GO TO (100, 200), METH
+C
+C Set coefficients for Adams methods. ----------------------------------
+ 100  IF (NQ .NE. 1) GO TO 110
+      EL(1) = ONE
+      EL(2) = ONE
+      TQ(1) = ONE
+      TQ(2) = TWO
+      TQ(3) = SIX*TQ(2)
+      TQ(5) = ONE
+      GO TO 300
+ 110  HSUM = H
+      EM(1) = ONE
+      FLOTNQ = FLOTL - ONE
+      DO 115 I = 2, L
+ 115    EM(I) = ZERO
+      DO 150 J = 1, NQM1
+        IF ((J .NE. NQM1) .OR. (NQWAIT .NE. 1)) GO TO 130
+        S = ONE
+        CSUM = ZERO
+        DO 120 I = 1, NQM1
+          CSUM = CSUM + S*EM(I)/REAL(I+1)
+ 120      S = -S
+        TQ(1) = EM(NQM1)/(FLOTNQ*CSUM)
+ 130    RXI = H/HSUM
+        DO 140 IBACK = 1, J
+          I = (J + 2) - IBACK
+ 140      EM(I) = EM(I) + EM(I-1)*RXI
+        HSUM = HSUM + TAU(J)
+ 150    CONTINUE
+C Compute integral from -1 to 0 of polynomial and of x times it. -------
+      S = ONE
+      EM0 = ZERO
+      CSUM = ZERO
+      DO 160 I = 1, NQ
+        FLOTI = REAL(I)
+        EM0 = EM0 + S*EM(I)/FLOTI
+        CSUM = CSUM + S*EM(I)/(FLOTI+ONE)
+ 160    S = -S
+C In EL, form coefficients of normalized integrated polynomial. --------
+      S = ONE/EM0
+      EL(1) = ONE
+      DO 170 I = 1, NQ
+ 170    EL(I+1) = S*EM(I)/REAL(I)
+      XI = HSUM/H
+      TQ(2) = XI*EM0/CSUM
+      TQ(5) = XI/EL(L)
+      IF (NQWAIT .NE. 1) GO TO 300
+C For higher order control constant, multiply polynomial by 1+x/xi(q). -
+      RXI = ONE/XI
+      DO 180 IBACK = 1, NQ
+        I = (L + 1) - IBACK
+ 180    EM(I) = EM(I) + EM(I-1)*RXI
+C Compute integral of polynomial. --------------------------------------
+      S = ONE
+      CSUM = ZERO
+      DO 190 I = 1, L
+        CSUM = CSUM + S*EM(I)/REAL(I+1)
+ 190    S = -S
+      TQ(3) = FLOTL*EM0/CSUM
+      GO TO 300
+C
+C Set coefficients for BDF methods. ------------------------------------
+ 200  DO 210 I = 3, L
+ 210    EL(I) = ZERO
+      EL(1) = ONE
+      EL(2) = ONE
+      ALPH0 = -ONE
+      AHATN0 = -ONE
+      HSUM = H
+      RXI = ONE
+      RXIS = ONE
+      IF (NQ .EQ. 1) GO TO 240
+      DO 230 J = 1, NQM2
+C In EL, construct coefficients of (1+x/xi(1))*...*(1+x/xi(j+1)). ------
+        HSUM = HSUM + TAU(J)
+        RXI = H/HSUM
+        JP1 = J + 1
+        ALPH0 = ALPH0 - ONE/REAL(JP1)
+        DO 220 IBACK = 1, JP1
+          I = (J + 3) - IBACK
+ 220      EL(I) = EL(I) + EL(I-1)*RXI
+ 230    CONTINUE
+      ALPH0 = ALPH0 - ONE/REAL(NQ)
+      RXIS = -EL(2) - ALPH0
+      HSUM = HSUM + TAU(NQM1)
+      RXI = H/HSUM
+      AHATN0 = -EL(2) - RXI
+      DO 235 IBACK = 1, NQ
+        I = (NQ + 2) - IBACK
+ 235    EL(I) = EL(I) + EL(I-1)*RXIS
+ 240  T1 = ONE - AHATN0 + ALPH0
+      T2 = ONE + REAL(NQ)*T1
+      TQ(2) = ABS(ALPH0*T2/T1)
+      TQ(5) = ABS(T2/(EL(L)*RXI/RXIS))
+      IF (NQWAIT .NE. 1) GO TO 300
+      CNQM1 = RXIS/EL(L)
+      T3 = ALPH0 + ONE/REAL(NQ)
+      T4 = AHATN0 + RXI
+      ELP = T3/(ONE - T4 + T3)
+      TQ(1) = ABS(ELP/CNQM1)
+      HSUM = HSUM + TAU(NQ)
+      RXI = H/HSUM
+      T5 = ALPH0 - ONE/REAL(NQ+1)
+      T6 = AHATN0 - RXI
+      ELP = T2/(ONE - T6 + T5)
+      TQ(3) = ABS(ELP*RXI*(FLOTL + ONE)*T5)
+ 300  TQ(4) = CORTES*TQ(2)
+      RETURN
+C----------------------- End of Subroutine ZVSET -----------------------
+      END
+*DECK ZVJUST
+      SUBROUTINE ZVJUST (YH, LDYH, IORD)
+      DOUBLE COMPLEX YH
+      INTEGER LDYH, IORD
+      DIMENSION YH(LDYH,*)
+C-----------------------------------------------------------------------
+C Call sequence input -- YH, LDYH, IORD
+C Call sequence output -- YH
+C COMMON block input -- NQ, METH, LMAX, HSCAL, TAU(13), N
+C COMMON block variables accessed:
+C     /ZVOD01/ -- HSCAL, TAU(13), LMAX, METH, N, NQ,
+C
+C Subroutines called by ZVJUST: DZAXPY
+C Function routines called by ZVJUST: None
+C-----------------------------------------------------------------------
+C This subroutine adjusts the YH array on reduction of order,
+C and also when the order is increased for the stiff option (METH = 2).
+C Communication with ZVJUST uses the following:
+C IORD  = An integer flag used when METH = 2 to indicate an order
+C         increase (IORD = +1) or an order decrease (IORD = -1).
+C HSCAL = Step size H used in scaling of Nordsieck array YH.
+C         (If IORD = +1, ZVJUST assumes that HSCAL = TAU(1).)
+C See References 1 and 2 for details.
+C-----------------------------------------------------------------------
+C
+C Type declarations for labeled COMMON block ZVOD01 --------------------
+C
+      DOUBLE PRECISION ACNRM, CCMXJ, CONP, CRATE, DRC, EL,
+     1     ETA, ETAMAX, H, HMIN, HMXI, HNEW, HRL1, HSCAL, PRL1,
+     2     RC, RL1, SRUR, TAU, TQ, TN, UROUND
+      INTEGER ICF, INIT, IPUP, JCUR, JSTART, JSV, KFLAG, KUTH,
+     1        L, LMAX, LYH, LEWT, LACOR, LSAVF, LWM, LIWM,
+     2        LOCJS, MAXORD, METH, MITER, MSBJ, MXHNIL, MXSTEP,
+     3        N, NEWH, NEWQ, NHNIL, NQ, NQNYH, NQWAIT, NSLJ,
+     4        NSLP, NYH
+C
+C Type declarations for local variables --------------------------------
+C
+      DOUBLE PRECISION ALPH0, ALPH1, HSUM, ONE, PROD, T1, XI,XIOLD, ZERO
+      INTEGER I, IBACK, J, JP1, LP1, NQM1, NQM2, NQP1
+C-----------------------------------------------------------------------
+C The following Fortran-77 declaration is to cause the values of the
+C listed (local) variables to be saved between calls to this integrator.
+C-----------------------------------------------------------------------
+      SAVE ONE, ZERO
+C
+      COMMON /ZVOD01/ ACNRM, CCMXJ, CONP, CRATE, DRC, EL(13), ETA,
+     1                ETAMAX, H, HMIN, HMXI, HNEW, HRL1, HSCAL, PRL1,
+     2                RC, RL1, SRUR, TAU(13), TQ(5), TN, UROUND,
+     3                ICF, INIT, IPUP, JCUR, JSTART, JSV, KFLAG, KUTH,
+     4                L, LMAX, LYH, LEWT, LACOR, LSAVF, LWM, LIWM,
+     5                LOCJS, MAXORD, METH, MITER, MSBJ, MXHNIL, MXSTEP,
+     6                N, NEWH, NEWQ, NHNIL, NQ, NQNYH, NQWAIT, NSLJ,
+     7                NSLP, NYH
+C
+      DATA ONE /1.0D0/, ZERO /0.0D0/
+C
+      IF ((NQ .EQ. 2) .AND. (IORD .NE. 1)) RETURN
+      NQM1 = NQ - 1
+      NQM2 = NQ - 2
+      GO TO (100, 200), METH
+C-----------------------------------------------------------------------
+C Nonstiff option...
+C Check to see if the order is being increased or decreased.
+C-----------------------------------------------------------------------
+ 100  CONTINUE
+      IF (IORD .EQ. 1) GO TO 180
+C Order decrease. ------------------------------------------------------
+      DO 110 J = 1, LMAX
+ 110    EL(J) = ZERO
+      EL(2) = ONE
+      HSUM = ZERO
+      DO 130 J = 1, NQM2
+C Construct coefficients of x*(x+xi(1))*...*(x+xi(j)). -----------------
+        HSUM = HSUM + TAU(J)
+        XI = HSUM/HSCAL
+        JP1 = J + 1
+        DO 120 IBACK = 1, JP1
+          I = (J + 3) - IBACK
+ 120      EL(I) = EL(I)*XI + EL(I-1)
+ 130    CONTINUE
+C Construct coefficients of integrated polynomial. ---------------------
+      DO 140 J = 2, NQM1
+ 140    EL(J+1) = REAL(NQ)*EL(J)/REAL(J)
+C Subtract correction terms from YH array. -----------------------------
+      DO 170 J = 3, NQ
+        DO 160 I = 1, N
+ 160      YH(I,J) = YH(I,J) - YH(I,L)*EL(J)
+ 170    CONTINUE
+      RETURN
+C Order increase. ------------------------------------------------------
+C Zero out next column in YH array. ------------------------------------
+ 180  CONTINUE
+      LP1 = L + 1
+      DO 190 I = 1, N
+ 190    YH(I,LP1) = ZERO
+      RETURN
+C-----------------------------------------------------------------------
+C Stiff option...
+C Check to see if the order is being increased or decreased.
+C-----------------------------------------------------------------------
+ 200  CONTINUE
+      IF (IORD .EQ. 1) GO TO 300
+C Order decrease. ------------------------------------------------------
+      DO 210 J = 1, LMAX
+ 210    EL(J) = ZERO
+      EL(3) = ONE
+      HSUM = ZERO
+      DO 230 J = 1,NQM2
+C Construct coefficients of x*x*(x+xi(1))*...*(x+xi(j)). ---------------
+        HSUM = HSUM + TAU(J)
+        XI = HSUM/HSCAL
+        JP1 = J + 1
+        DO 220 IBACK = 1, JP1
+          I = (J + 4) - IBACK
+ 220      EL(I) = EL(I)*XI + EL(I-1)
+ 230    CONTINUE
+C Subtract correction terms from YH array. -----------------------------
+      DO 250 J = 3,NQ
+        DO 240 I = 1, N
+ 240      YH(I,J) = YH(I,J) - YH(I,L)*EL(J)
+ 250    CONTINUE
+      RETURN
+C Order increase. ------------------------------------------------------
+ 300  DO 310 J = 1, LMAX
+ 310    EL(J) = ZERO
+      EL(3) = ONE
+      ALPH0 = -ONE
+      ALPH1 = ONE
+      PROD = ONE
+      XIOLD = ONE
+      HSUM = HSCAL
+      IF (NQ .EQ. 1) GO TO 340
+      DO 330 J = 1, NQM1
+C Construct coefficients of x*x*(x+xi(1))*...*(x+xi(j)). ---------------
+        JP1 = J + 1
+        HSUM = HSUM + TAU(JP1)
+        XI = HSUM/HSCAL
+        PROD = PROD*XI
+        ALPH0 = ALPH0 - ONE/REAL(JP1)
+        ALPH1 = ALPH1 + ONE/XI
+        DO 320 IBACK = 1, JP1
+          I = (J + 4) - IBACK
+ 320      EL(I) = EL(I)*XIOLD + EL(I-1)
+        XIOLD = XI
+ 330    CONTINUE
+ 340  CONTINUE
+      T1 = (-ALPH0 - ALPH1)/PROD
+C Load column L + 1 in YH array. ---------------------------------------
+      LP1 = L + 1
+      DO 350 I = 1, N
+ 350    YH(I,LP1) = T1*YH(I,LMAX)
+C Add correction terms to YH array. ------------------------------------
+      NQP1 = NQ + 1
+      DO 370 J = 3, NQP1
+        CALL DZAXPY (N, EL(J), YH(1,LP1), 1, YH(1,J), 1 )
+ 370  CONTINUE
+      RETURN
+C----------------------- End of Subroutine ZVJUST ----------------------
+      END
+*DECK ZVNLSD
+      SUBROUTINE ZVNLSD (Y, YH, LDYH, VSAV, SAVF, EWT, ACOR, IWM, WM,
+     1                 F, JAC, PDUM, NFLAG, RPAR, IPAR)
+      EXTERNAL F, JAC, PDUM
+      DOUBLE COMPLEX Y, YH, VSAV, SAVF, ACOR, WM
+      DOUBLE PRECISION EWT
+      INTEGER LDYH, IWM, NFLAG, IPAR
+      DIMENSION Y(*), YH(LDYH,*), VSAV(*), SAVF(*), EWT(*), ACOR(*),
+     1          IWM(*), WM(*), RPAR(*), IPAR(*)
+C-----------------------------------------------------------------------
+C Call sequence input -- Y, YH, LDYH, SAVF, EWT, ACOR, IWM, WM,
+C                        F, JAC, NFLAG, RPAR, IPAR
+C Call sequence output -- YH, ACOR, WM, IWM, NFLAG
+C COMMON block variables accessed:
+C     /ZVOD01/ ACNRM, CRATE, DRC, H, RC, RL1, TQ(5), TN, ICF,
+C                JCUR, METH, MITER, N, NSLP
+C     /ZVOD02/ HU, NCFN, NETF, NFE, NJE, NLU, NNI, NQU, NST
+C
+C Subroutines called by ZVNLSD: F, DZAXPY, ZCOPY, DZSCAL, ZVJAC, ZVSOL
+C Function routines called by ZVNLSD: ZVNORM
+C-----------------------------------------------------------------------
+C Subroutine ZVNLSD is a nonlinear system solver, which uses functional
+C iteration or a chord (modified Newton) method.  For the chord method
+C direct linear algebraic system solvers are used.  Subroutine ZVNLSD
+C then handles the corrector phase of this integration package.
+C
+C Communication with ZVNLSD is done with the following variables. (For
+C
+C Y          = The dependent variable, a vector of length N, input.
+C YH         = The Nordsieck (Taylor) array, LDYH by LMAX, input
+C              and output.  On input, it contains predicted values.
+C LDYH       = A constant .ge. N, the first dimension of YH, input.
+C VSAV       = Unused work array.
+C SAVF       = A work array of length N.
+C EWT        = An error weight vector of length N, input.
+C ACOR       = A work array of length N, used for the accumulated
+C              corrections to the predicted y vector.
+C WM,IWM     = Complex and integer work arrays associated with matrix
+C              operations in chord iteration (MITER .ne. 0).
+C F          = Dummy name for user-supplied routine for f.
+C JAC        = Dummy name for user-supplied Jacobian routine.
+C PDUM       = Unused dummy subroutine name.  Included for uniformity
+C              over collection of integrators.
+C NFLAG      = Input/output flag, with values and meanings as follows:
+C              INPUT
+C                  0 first call for this time step.
+C                 -1 convergence failure in previous call to ZVNLSD.
+C                 -2 error test failure in ZVSTEP.
+C              OUTPUT
+C                  0 successful completion of nonlinear solver.
+C                 -1 convergence failure or singular matrix.
+C                 -2 unrecoverable error in matrix preprocessing
+C                    (cannot occur here).
+C                 -3 unrecoverable error in solution (cannot occur
+C                    here).
+C RPAR, IPAR = User's real/complex and integer work arrays.
+C
+C IPUP       = Own variable flag with values and meanings as follows:
+C              0,            do not update the Newton matrix.
+C              MITER .ne. 0, update Newton matrix, because it is the
+C                            initial step, order was changed, the error
+C                            test failed, or an update is indicated by
+C                            the scalar RC or step counter NST.
+C
+C For more details, see comments in driver subroutine.
+C-----------------------------------------------------------------------
+C Type declarations for labeled COMMON block ZVOD01 --------------------
+C
+      DOUBLE PRECISION ACNRM, CCMXJ, CONP, CRATE, DRC, EL,
+     1     ETA, ETAMAX, H, HMIN, HMXI, HNEW, HRL1, HSCAL, PRL1,
+     2     RC, RL1, SRUR, TAU, TQ, TN, UROUND
+      INTEGER ICF, INIT, IPUP, JCUR, JSTART, JSV, KFLAG, KUTH,
+     1        L, LMAX, LYH, LEWT, LACOR, LSAVF, LWM, LIWM,
+     2        LOCJS, MAXORD, METH, MITER, MSBJ, MXHNIL, MXSTEP,
+     3        N, NEWH, NEWQ, NHNIL, NQ, NQNYH, NQWAIT, NSLJ,
+     4        NSLP, NYH
+C
+C Type declarations for labeled COMMON block ZVOD02 --------------------
+C
+      DOUBLE PRECISION HU
+      INTEGER NCFN, NETF, NFE, NJE, NLU, NNI, NQU, NST
+C
+C Type declarations for local variables --------------------------------
+C
+      DOUBLE PRECISION CCMAX, CRDOWN, CSCALE, DCON, DEL, DELP, ONE,
+     1     RDIV, TWO, ZERO
+      INTEGER I, IERPJ, IERSL, M, MAXCOR, MSBP
+C
+C Type declaration for function subroutines called ---------------------
+C
+      DOUBLE PRECISION ZVNORM
+C-----------------------------------------------------------------------
+C The following Fortran-77 declaration is to cause the values of the
+C listed (local) variables to be saved between calls to this integrator.
+C-----------------------------------------------------------------------
+      SAVE CCMAX, CRDOWN, MAXCOR, MSBP, RDIV, ONE, TWO, ZERO
+C
+      COMMON /ZVOD01/ ACNRM, CCMXJ, CONP, CRATE, DRC, EL(13), ETA,
+     1                ETAMAX, H, HMIN, HMXI, HNEW, HRL1, HSCAL, PRL1,
+     2                RC, RL1, SRUR, TAU(13), TQ(5), TN, UROUND,
+     3                ICF, INIT, IPUP, JCUR, JSTART, JSV, KFLAG, KUTH,
+     4                L, LMAX, LYH, LEWT, LACOR, LSAVF, LWM, LIWM,
+     5                LOCJS, MAXORD, METH, MITER, MSBJ, MXHNIL, MXSTEP,
+     6                N, NEWH, NEWQ, NHNIL, NQ, NQNYH, NQWAIT, NSLJ,
+     7                NSLP, NYH
+      COMMON /ZVOD02/ HU, NCFN, NETF, NFE, NJE, NLU, NNI, NQU, NST
+C
+      DATA CCMAX /0.3D0/, CRDOWN /0.3D0/, MAXCOR /3/, MSBP /20/,
+     1     RDIV  /2.0D0/
+      DATA ONE /1.0D0/, TWO /2.0D0/, ZERO /0.0D0/
+C-----------------------------------------------------------------------
+C On the first step, on a change of method order, or after a
+C nonlinear convergence failure with NFLAG = -2, set IPUP = MITER
+C to force a Jacobian update when MITER .ne. 0.
+C-----------------------------------------------------------------------
+      IF (JSTART .EQ. 0) NSLP = 0
+      IF (NFLAG .EQ. 0) ICF = 0
+      IF (NFLAG .EQ. -2) IPUP = MITER
+      IF ( (JSTART .EQ. 0) .OR. (JSTART .EQ. -1) ) IPUP = MITER
+C If this is functional iteration, set CRATE .eq. 1 and drop to 220
+      IF (MITER .EQ. 0) THEN
+        CRATE = ONE
+        GO TO 220
+      ENDIF
+C-----------------------------------------------------------------------
+C RC is the ratio of new to old values of the coefficient H/EL(2)=h/l1.
+C When RC differs from 1 by more than CCMAX, IPUP is set to MITER
+C to force ZVJAC to be called, if a Jacobian is involved.
+C In any case, ZVJAC is called at least every MSBP steps.
+C-----------------------------------------------------------------------
+      DRC = ABS(RC-ONE)
+      IF (DRC .GT. CCMAX .OR. NST .GE. NSLP+MSBP) IPUP = MITER
+C-----------------------------------------------------------------------
+C Up to MAXCOR corrector iterations are taken.  A convergence test is
+C made on the r.m.s. norm of each correction, weighted by the error
+C weight vector EWT.  The sum of the corrections is accumulated in the
+C vector ACOR(i).  The YH array is not altered in the corrector loop.
+C-----------------------------------------------------------------------
+ 220  M = 0
+      DELP = ZERO
+      CALL ZCOPY (N, YH(1,1), 1, Y, 1 )
+      CALL F (N, TN, Y, SAVF, RPAR, IPAR)
+      NFE = NFE + 1
+      IF (IPUP .LE. 0) GO TO 250
+C-----------------------------------------------------------------------
+C If indicated, the matrix P = I - h*rl1*J is reevaluated and
+C preprocessed before starting the corrector iteration.  IPUP is set
+C to 0 as an indicator that this has been done.
+C-----------------------------------------------------------------------
+      CALL ZVJAC (Y, YH, LDYH, EWT, ACOR, SAVF, WM, IWM, F, JAC, IERPJ,
+     1           RPAR, IPAR)
+      IPUP = 0
+      RC = ONE
+      DRC = ZERO
+      CRATE = ONE
+      NSLP = NST
+C If matrix is singular, take error return to force cut in step size. --
+      IF (IERPJ .NE. 0) GO TO 430
+ 250  DO 260 I = 1,N
+ 260    ACOR(I) = ZERO
+C This is a looping point for the corrector iteration. -----------------
+ 270  IF (MITER .NE. 0) GO TO 350
+C-----------------------------------------------------------------------
+C In the case of functional iteration, update Y directly from
+C the result of the last function evaluation.
+C-----------------------------------------------------------------------
+      DO 280 I = 1,N
+ 280    SAVF(I) = RL1*(H*SAVF(I) - YH(I,2))
+      DO 290 I = 1,N
+ 290    Y(I) = SAVF(I) - ACOR(I)
+      DEL = ZVNORM (N, Y, EWT)
+      DO 300 I = 1,N
+ 300    Y(I) = YH(I,1) + SAVF(I)
+      CALL ZCOPY (N, SAVF, 1, ACOR, 1)
+      GO TO 400
+C-----------------------------------------------------------------------
+C In the case of the chord method, compute the corrector error,
+C and solve the linear system with that as right-hand side and
+C P as coefficient matrix.  The correction is scaled by the factor
+C 2/(1+RC) to account for changes in h*rl1 since the last ZVJAC call.
+C-----------------------------------------------------------------------
+ 350  DO 360 I = 1,N
+ 360    Y(I) = (RL1*H)*SAVF(I) - (RL1*YH(I,2) + ACOR(I))
+      CALL ZVSOL (WM, IWM, Y, IERSL)
+      NNI = NNI + 1
+      IF (IERSL .GT. 0) GO TO 410
+      IF (METH .EQ. 2 .AND. RC .NE. ONE) THEN
+        CSCALE = TWO/(ONE + RC)
+        CALL DZSCAL (N, CSCALE, Y, 1)
+      ENDIF
+      DEL = ZVNORM (N, Y, EWT)
+      CALL DZAXPY (N, ONE, Y, 1, ACOR, 1)
+      DO 380 I = 1,N
+ 380    Y(I) = YH(I,1) + ACOR(I)
+C-----------------------------------------------------------------------
+C Test for convergence.  If M .gt. 0, an estimate of the convergence
+C rate constant is stored in CRATE, and this is used in the test.
+C-----------------------------------------------------------------------
+ 400  IF (M .NE. 0) CRATE = MAX(CRDOWN*CRATE,DEL/DELP)
+      DCON = DEL*MIN(ONE,CRATE)/TQ(4)
+      IF (DCON .LE. ONE) GO TO 450
+      M = M + 1
+      IF (M .EQ. MAXCOR) GO TO 410
+      IF (M .GE. 2 .AND. DEL .GT. RDIV*DELP) GO TO 410
+      DELP = DEL
+      CALL F (N, TN, Y, SAVF, RPAR, IPAR)
+      NFE = NFE + 1
+      GO TO 270
+C
+ 410  IF (MITER .EQ. 0 .OR. JCUR .EQ. 1) GO TO 430
+      ICF = 1
+      IPUP = MITER
+      GO TO 220
+C
+ 430  CONTINUE
+      NFLAG = -1
+      ICF = 2
+      IPUP = MITER
+      RETURN
+C
+C Return for successful step. ------------------------------------------
+ 450  NFLAG = 0
+      JCUR = 0
+      ICF = 0
+      IF (M .EQ. 0) ACNRM = DEL
+      IF (M .GT. 0) ACNRM = ZVNORM (N, ACOR, EWT)
+      RETURN
+C----------------------- End of Subroutine ZVNLSD ----------------------
+      END
+*DECK ZVJAC
+      SUBROUTINE ZVJAC (Y, YH, LDYH, EWT, FTEM, SAVF, WM, IWM, F, JAC,
+     1                 IERPJ, RPAR, IPAR)
+      EXTERNAL F, JAC
+      DOUBLE COMPLEX Y, YH, FTEM, SAVF, WM
+      DOUBLE PRECISION EWT
+      INTEGER LDYH, IWM, IERPJ, IPAR
+      DIMENSION Y(*), YH(LDYH,*), EWT(*), FTEM(*), SAVF(*),
+     1   WM(*), IWM(*), RPAR(*), IPAR(*)
+C-----------------------------------------------------------------------
+C Call sequence input -- Y, YH, LDYH, EWT, FTEM, SAVF, WM, IWM,
+C                        F, JAC, RPAR, IPAR
+C Call sequence output -- WM, IWM, IERPJ
+C COMMON block variables accessed:
+C     /ZVOD01/  CCMXJ, DRC, H, HRL1, RL1, SRUR, TN, UROUND, ICF, JCUR,
+C               LOCJS, MITER, MSBJ, N, NSLJ
+C     /ZVOD02/  NFE, NST, NJE, NLU
+C
+C Subroutines called by ZVJAC: F, JAC, ZACOPY, ZCOPY, ZGBFA, ZGEFA,
+C                              DZSCAL
+C Function routines called by ZVJAC: ZVNORM
+C-----------------------------------------------------------------------
+C ZVJAC is called by ZVNLSD to compute and process the matrix
+C P = I - h*rl1*J , where J is an approximation to the Jacobian.
+C Here J is computed by the user-supplied routine JAC if
+C MITER = 1 or 4, or by finite differencing if MITER = 2, 3, or 5.
+C If MITER = 3, a diagonal approximation to J is used.
+C If JSV = -1, J is computed from scratch in all cases.
+C If JSV = 1 and MITER = 1, 2, 4, or 5, and if the saved value of J is
+C considered acceptable, then P is constructed from the saved J.
+C J is stored in wm and replaced by P.  If MITER .ne. 3, P is then
+C subjected to LU decomposition in preparation for later solution
+C of linear systems with P as coefficient matrix. This is done
+C by ZGEFA if MITER = 1 or 2, and by ZGBFA if MITER = 4 or 5.
+C
+C Communication with ZVJAC is done with the following variables.  (For
+C Y          = Vector containing predicted values on entry.
+C YH         = The Nordsieck array, an LDYH by LMAX array, input.
+C LDYH       = A constant .ge. N, the first dimension of YH, input.
+C EWT        = An error weight vector of length N.
+C SAVF       = Array containing f evaluated at predicted y, input.
+C WM         = Complex work space for matrices.  In the output, it
+C              contains the inverse diagonal matrix if MITER = 3 and
+C              the LU decomposition of P if MITER is 1, 2 , 4, or 5.
+C              Storage of the saved Jacobian starts at WM(LOCJS).
+C IWM        = Integer work space containing pivot information,
+C              starting at IWM(31), if MITER is 1, 2, 4, or 5.
+C              IWM also contains band parameters ML = IWM(1) and
+C              MU = IWM(2) if MITER is 4 or 5.
+C F          = Dummy name for the user-supplied subroutine for f.
+C JAC        = Dummy name for the user-supplied Jacobian subroutine.
+C RPAR, IPAR = User's real/complex and integer work arrays.
+C RL1        = 1/EL(2) (input).
+C IERPJ      = Output error flag,  = 0 if no trouble, 1 if the P
+C              matrix is found to be singular.
+C JCUR       = Output flag to indicate whether the Jacobian matrix
+C              (or approximation) is now current.
+C              JCUR = 0 means J is not current.
+C              JCUR = 1 means J is current.
+C-----------------------------------------------------------------------
+C
+C Type declarations for labeled COMMON block ZVOD01 --------------------
+C
+      DOUBLE PRECISION ACNRM, CCMXJ, CONP, CRATE, DRC, EL,
+     1     ETA, ETAMAX, H, HMIN, HMXI, HNEW, HRL1, HSCAL, PRL1,
+     2     RC, RL1, SRUR, TAU, TQ, TN, UROUND
+      INTEGER ICF, INIT, IPUP, JCUR, JSTART, JSV, KFLAG, KUTH,
+     1        L, LMAX, LYH, LEWT, LACOR, LSAVF, LWM, LIWM,
+     2        LOCJS, MAXORD, METH, MITER, MSBJ, MXHNIL, MXSTEP,
+     3        N, NEWH, NEWQ, NHNIL, NQ, NQNYH, NQWAIT, NSLJ,
+     4        NSLP, NYH
+C
+C Type declarations for labeled COMMON block ZVOD02 --------------------
+C
+      DOUBLE PRECISION HU
+      INTEGER NCFN, NETF, NFE, NJE, NLU, NNI, NQU, NST
+C
+C Type declarations for local variables --------------------------------
+C
+      DOUBLE COMPLEX DI, R1, YI, YJ, YJJ
+      DOUBLE PRECISION CON, FAC, ONE, PT1, R, R0, THOU, ZERO
+      INTEGER I, I1, I2, IER, II, J, J1, JJ, JOK, LENP, MBA, MBAND,
+     1        MEB1, MEBAND, ML, ML1, MU, NP1
+C
+C Type declaration for function subroutines called ---------------------
+C
+      DOUBLE PRECISION ZVNORM
+C-----------------------------------------------------------------------
+C The following Fortran-77 declaration is to cause the values of the
+C listed (local) variables to be saved between calls to this subroutine.
+C-----------------------------------------------------------------------
+      SAVE ONE, PT1, THOU, ZERO
+C-----------------------------------------------------------------------
+      COMMON /ZVOD01/ ACNRM, CCMXJ, CONP, CRATE, DRC, EL(13), ETA,
+     1                ETAMAX, H, HMIN, HMXI, HNEW, HRL1, HSCAL, PRL1,
+     2                RC, RL1, SRUR, TAU(13), TQ(5), TN, UROUND,
+     3                ICF, INIT, IPUP, JCUR, JSTART, JSV, KFLAG, KUTH,
+     4                L, LMAX, LYH, LEWT, LACOR, LSAVF, LWM, LIWM,
+     5                LOCJS, MAXORD, METH, MITER, MSBJ, MXHNIL, MXSTEP,
+     6                N, NEWH, NEWQ, NHNIL, NQ, NQNYH, NQWAIT, NSLJ,
+     7                NSLP, NYH
+      COMMON /ZVOD02/ HU, NCFN, NETF, NFE, NJE, NLU, NNI, NQU, NST
+C
+      DATA ONE /1.0D0/, THOU /1000.0D0/, ZERO /0.0D0/, PT1 /0.1D0/
+C
+      IERPJ = 0
+      HRL1 = H*RL1
+C See whether J should be evaluated (JOK = -1) or not (JOK = 1). -------
+      JOK = JSV
+      IF (JSV .EQ. 1) THEN
+        IF (NST .EQ. 0 .OR. NST .GT. NSLJ+MSBJ) JOK = -1
+        IF (ICF .EQ. 1 .AND. DRC .LT. CCMXJ) JOK = -1
+        IF (ICF .EQ. 2) JOK = -1
+      ENDIF
+C End of setting JOK. --------------------------------------------------
+C
+      IF (JOK .EQ. -1 .AND. MITER .EQ. 1) THEN
+C If JOK = -1 and MITER = 1, call JAC to evaluate Jacobian. ------------
+      NJE = NJE + 1
+      NSLJ = NST
+      JCUR = 1
+      LENP = N*N
+      DO 110 I = 1,LENP
+ 110    WM(I) = ZERO
+      CALL JAC (N, TN, Y, 0, 0, WM, N, RPAR, IPAR)
+      IF (JSV .EQ. 1) CALL ZCOPY (LENP, WM, 1, WM(LOCJS), 1)
+      ENDIF
+C
+      IF (JOK .EQ. -1 .AND. MITER .EQ. 2) THEN
+C If MITER = 2, make N calls to F to approximate the Jacobian. ---------
+      NJE = NJE + 1
+      NSLJ = NST
+      JCUR = 1
+      FAC = ZVNORM (N, SAVF, EWT)
+      R0 = THOU*ABS(H)*UROUND*REAL(N)*FAC
+      IF (R0 .EQ. ZERO) R0 = ONE
+      J1 = 0
+      DO 230 J = 1,N
+        YJ = Y(J)
+        R = MAX(SRUR*ABS(YJ),R0/EWT(J))
+        Y(J) = Y(J) + R
+        FAC = ONE/R
+        CALL F (N, TN, Y, FTEM, RPAR, IPAR)
+        DO 220 I = 1,N
+ 220      WM(I+J1) = (FTEM(I) - SAVF(I))*FAC
+        Y(J) = YJ
+        J1 = J1 + N
+ 230    CONTINUE
+      NFE = NFE + N
+      LENP = N*N
+      IF (JSV .EQ. 1) CALL ZCOPY (LENP, WM, 1, WM(LOCJS), 1)
+      ENDIF
+C
+      IF (JOK .EQ. 1 .AND. (MITER .EQ. 1 .OR. MITER .EQ. 2)) THEN
+      JCUR = 0
+      LENP = N*N
+      CALL ZCOPY (LENP, WM(LOCJS), 1, WM, 1)
+      ENDIF
+C
+      IF (MITER .EQ. 1 .OR. MITER .EQ. 2) THEN
+C Multiply Jacobian by scalar, add identity, and do LU decomposition. --
+      CON = -HRL1
+      CALL DZSCAL (LENP, CON, WM, 1)
+      J = 1
+      NP1 = N + 1
+      DO 250 I = 1,N
+        WM(J) = WM(J) + ONE
+ 250    J = J + NP1
+      NLU = NLU + 1
+      CALL ZGEFA (WM, N, N, IWM(31), IER)
+      IF (IER .NE. 0) IERPJ = 1
+      RETURN
+      ENDIF
+C End of code block for MITER = 1 or 2. --------------------------------
+C
+      IF (MITER .EQ. 3) THEN
+C If MITER = 3, construct a diagonal approximation to J and P. ---------
+      NJE = NJE + 1
+      JCUR = 1
+      R = RL1*PT1
+      DO 310 I = 1,N
+ 310    Y(I) = Y(I) + R*(H*SAVF(I) - YH(I,2))
+      CALL F (N, TN, Y, WM, RPAR, IPAR)
+      NFE = NFE + 1
+      DO 320 I = 1,N
+        R1 = H*SAVF(I) - YH(I,2)
+        DI = PT1*R1 - H*(WM(I) - SAVF(I))
+        WM(I) = ONE
+        IF (ABS(R1) .LT. UROUND/EWT(I)) GO TO 320
+        IF (ABS(DI) .EQ. ZERO) GO TO 330
+        WM(I) = PT1*R1/DI
+ 320    CONTINUE
+      RETURN
+ 330  IERPJ = 1
+      RETURN
+      ENDIF
+C End of code block for MITER = 3. -------------------------------------
+C
+C Set constants for MITER = 4 or 5. ------------------------------------
+      ML = IWM(1)
+      MU = IWM(2)
+      ML1 = ML + 1
+      MBAND = ML + MU + 1
+      MEBAND = MBAND + ML
+      LENP = MEBAND*N
+C
+      IF (JOK .EQ. -1 .AND. MITER .EQ. 4) THEN
+C If JOK = -1 and MITER = 4, call JAC to evaluate Jacobian. ------------
+      NJE = NJE + 1
+      NSLJ = NST
+      JCUR = 1
+      DO 410 I = 1,LENP
+ 410    WM(I) = ZERO
+      CALL JAC (N, TN, Y, ML, MU, WM(ML1), MEBAND, RPAR, IPAR)
+      IF (JSV .EQ. 1)
+     1   CALL ZACOPY (MBAND, N, WM(ML1), MEBAND, WM(LOCJS), MBAND)
+      ENDIF
+C
+      IF (JOK .EQ. -1 .AND. MITER .EQ. 5) THEN
+C If MITER = 5, make ML+MU+1 calls to F to approximate the Jacobian. ---
+      NJE = NJE + 1
+      NSLJ = NST
+      JCUR = 1
+      MBA = MIN(MBAND,N)
+      MEB1 = MEBAND - 1
+      FAC = ZVNORM (N, SAVF, EWT)
+      R0 = THOU*ABS(H)*UROUND*REAL(N)*FAC
+      IF (R0 .EQ. ZERO) R0 = ONE
+      DO 560 J = 1,MBA
+        DO 530 I = J,N,MBAND
+          YI = Y(I)
+          R = MAX(SRUR*ABS(YI),R0/EWT(I))
+ 530      Y(I) = Y(I) + R
+        CALL F (N, TN, Y, FTEM, RPAR, IPAR)
+        DO 550 JJ = J,N,MBAND
+          Y(JJ) = YH(JJ,1)
+          YJJ = Y(JJ)
+          R = MAX(SRUR*ABS(YJJ),R0/EWT(JJ))
+          FAC = ONE/R
+          I1 = MAX(JJ-MU,1)
+          I2 = MIN(JJ+ML,N)
+          II = JJ*MEB1 - ML
+          DO 540 I = I1,I2
+ 540        WM(II+I) = (FTEM(I) - SAVF(I))*FAC
+ 550      CONTINUE
+ 560    CONTINUE
+      NFE = NFE + MBA
+      IF (JSV .EQ. 1)
+     1   CALL ZACOPY (MBAND, N, WM(ML1), MEBAND, WM(LOCJS), MBAND)
+      ENDIF
+C
+      IF (JOK .EQ. 1) THEN
+      JCUR = 0
+      CALL ZACOPY (MBAND, N, WM(LOCJS), MBAND, WM(ML1), MEBAND)
+      ENDIF
+C
+C Multiply Jacobian by scalar, add identity, and do LU decomposition.
+      CON = -HRL1
+      CALL DZSCAL (LENP, CON, WM, 1 )
+      II = MBAND
+      DO 580 I = 1,N
+        WM(II) = WM(II) + ONE
+ 580    II = II + MEBAND
+      NLU = NLU + 1
+      CALL ZGBFA (WM, MEBAND, N, ML, MU, IWM(31), IER)
+      IF (IER .NE. 0) IERPJ = 1
+      RETURN
+C End of code block for MITER = 4 or 5. --------------------------------
+C
+C----------------------- End of Subroutine ZVJAC -----------------------
+      END
+*DECK ZACOPY
+      SUBROUTINE ZACOPY (NROW, NCOL, A, NROWA, B, NROWB)
+      DOUBLE COMPLEX A, B
+      INTEGER NROW, NCOL, NROWA, NROWB
+      DIMENSION A(NROWA,NCOL), B(NROWB,NCOL)
+C-----------------------------------------------------------------------
+C Call sequence input -- NROW, NCOL, A, NROWA, NROWB
+C Call sequence output -- B
+C COMMON block variables accessed -- None
+C
+C Subroutines called by ZACOPY: ZCOPY
+C Function routines called by ZACOPY: None
+C-----------------------------------------------------------------------
+C This routine copies one rectangular array, A, to another, B,
+C where A and B may have different row dimensions, NROWA and NROWB.
+C The data copied consists of NROW rows and NCOL columns.
+C-----------------------------------------------------------------------
+      INTEGER IC
+C
+      DO 20 IC = 1,NCOL
+        CALL ZCOPY (NROW, A(1,IC), 1, B(1,IC), 1)
+ 20     CONTINUE
+C
+      RETURN
+C----------------------- End of Subroutine ZACOPY ----------------------
+      END
+*DECK ZVSOL
+      SUBROUTINE ZVSOL (WM, IWM, X, IERSL)
+      DOUBLE COMPLEX WM, X
+      INTEGER IWM, IERSL
+      DIMENSION WM(*), IWM(*), X(*)
+C-----------------------------------------------------------------------
+C Call sequence input -- WM, IWM, X
+C Call sequence output -- X, IERSL
+C COMMON block variables accessed:
+C     /ZVOD01/ -- H, HRL1, RL1, MITER, N
+C
+C Subroutines called by ZVSOL: ZGESL, ZGBSL
+C Function routines called by ZVSOL: None
+C-----------------------------------------------------------------------
+C This routine manages the solution of the linear system arising from
+C a chord iteration.  It is called if MITER .ne. 0.
+C If MITER is 1 or 2, it calls ZGESL to accomplish this.
+C If MITER = 3 it updates the coefficient H*RL1 in the diagonal
+C matrix, and then computes the solution.
+C If MITER is 4 or 5, it calls ZGBSL.
+C Communication with ZVSOL uses the following variables:
+C WM    = Real work space containing the inverse diagonal matrix if
+C         MITER = 3 and the LU decomposition of the matrix otherwise.
+C IWM   = Integer work space containing pivot information, starting at
+C         IWM(31), if MITER is 1, 2, 4, or 5.  IWM also contains band
+C         parameters ML = IWM(1) and MU = IWM(2) if MITER is 4 or 5.
+C X     = The right-hand side vector on input, and the solution vector
+C         on output, of length N.
+C IERSL = Output flag.  IERSL = 0 if no trouble occurred.
+C         IERSL = 1 if a singular matrix arose with MITER = 3.
+C-----------------------------------------------------------------------
+C
+C Type declarations for labeled COMMON block ZVOD01 --------------------
+C
+      DOUBLE PRECISION ACNRM, CCMXJ, CONP, CRATE, DRC, EL,
+     1     ETA, ETAMAX, H, HMIN, HMXI, HNEW, HRL1, HSCAL, PRL1,
+     2     RC, RL1, SRUR, TAU, TQ, TN, UROUND
+      INTEGER ICF, INIT, IPUP, JCUR, JSTART, JSV, KFLAG, KUTH,
+     1        L, LMAX, LYH, LEWT, LACOR, LSAVF, LWM, LIWM,
+     2        LOCJS, MAXORD, METH, MITER, MSBJ, MXHNIL, MXSTEP,
+     3        N, NEWH, NEWQ, NHNIL, NQ, NQNYH, NQWAIT, NSLJ,
+     4        NSLP, NYH
+C
+C Type declarations for local variables --------------------------------
+C
+      DOUBLE COMPLEX DI
+      DOUBLE PRECISION ONE, PHRL1, R, ZERO
+      INTEGER I, MEBAND, ML, MU
+C-----------------------------------------------------------------------
+C The following Fortran-77 declaration is to cause the values of the
+C listed (local) variables to be saved between calls to this integrator.
+C-----------------------------------------------------------------------
+      SAVE ONE, ZERO
+C
+      COMMON /ZVOD01/ ACNRM, CCMXJ, CONP, CRATE, DRC, EL(13), ETA,
+     1                ETAMAX, H, HMIN, HMXI, HNEW, HRL1, HSCAL, PRL1,
+     2                RC, RL1, SRUR, TAU(13), TQ(5), TN, UROUND,
+     3                ICF, INIT, IPUP, JCUR, JSTART, JSV, KFLAG, KUTH,
+     4                L, LMAX, LYH, LEWT, LACOR, LSAVF, LWM, LIWM,
+     5                LOCJS, MAXORD, METH, MITER, MSBJ, MXHNIL, MXSTEP,
+     6                N, NEWH, NEWQ, NHNIL, NQ, NQNYH, NQWAIT, NSLJ,
+     7                NSLP, NYH
+C
+      DATA ONE /1.0D0/, ZERO /0.0D0/
+C
+      IERSL = 0
+      GO TO (100, 100, 300, 400, 400), MITER
+ 100  CALL ZGESL (WM, N, N, IWM(31), X, 0)
+      RETURN
+C
+ 300  PHRL1 = HRL1
+      HRL1 = H*RL1
+      IF (HRL1 .EQ. PHRL1) GO TO 330
+      R = HRL1/PHRL1
+      DO 320 I = 1,N
+        DI = ONE - R*(ONE - ONE/WM(I))
+        IF (ABS(DI) .EQ. ZERO) GO TO 390
+ 320    WM(I) = ONE/DI
+C
+ 330  DO 340 I = 1,N
+ 340    X(I) = WM(I)*X(I)
+      RETURN
+ 390  IERSL = 1
+      RETURN
+C
+ 400  ML = IWM(1)
+      MU = IWM(2)
+      MEBAND = 2*ML + MU + 1
+      CALL ZGBSL (WM, MEBAND, N, ML, MU, IWM(31), X, 0)
+      RETURN
+C----------------------- End of Subroutine ZVSOL -----------------------
+      END
+*DECK ZVSRCO
+      SUBROUTINE ZVSRCO (RSAV, ISAV, JOB)
+      DOUBLE PRECISION RSAV
+      INTEGER ISAV, JOB
+      DIMENSION RSAV(*), ISAV(*)
+C-----------------------------------------------------------------------
+C Call sequence input -- RSAV, ISAV, JOB
+C Call sequence output -- RSAV, ISAV
+C COMMON block variables accessed -- All of /ZVOD01/ and /ZVOD02/
+C
+C Subroutines/functions called by ZVSRCO: None
+C-----------------------------------------------------------------------
+C This routine saves or restores (depending on JOB) the contents of the
+C COMMON blocks ZVOD01 and ZVOD02, which are used internally by ZVODE.
+C
+C RSAV = real array of length 51 or more.
+C ISAV = integer array of length 41 or more.
+C JOB  = flag indicating to save or restore the COMMON blocks:
+C        JOB  = 1 if COMMON is to be saved (written to RSAV/ISAV).
+C        JOB  = 2 if COMMON is to be restored (read from RSAV/ISAV).
+C        A call with JOB = 2 presumes a prior call with JOB = 1.
+C-----------------------------------------------------------------------
+      DOUBLE PRECISION RVOD1, RVOD2
+      INTEGER IVOD1, IVOD2
+      INTEGER I, LENIV1, LENIV2, LENRV1, LENRV2
+C-----------------------------------------------------------------------
+C The following Fortran-77 declaration is to cause the values of the
+C listed (local) variables to be saved between calls to this integrator.
+C-----------------------------------------------------------------------
+      SAVE LENRV1, LENIV1, LENRV2, LENIV2
+C
+      COMMON /ZVOD01/ RVOD1(50), IVOD1(33)
+      COMMON /ZVOD02/ RVOD2(1), IVOD2(8)
+      DATA LENRV1/50/, LENIV1/33/, LENRV2/1/, LENIV2/8/
+C
+      IF (JOB .EQ. 2) GO TO 100
+      DO 10 I = 1,LENRV1
+ 10     RSAV(I) = RVOD1(I)
+      DO 15 I = 1,LENRV2
+ 15     RSAV(LENRV1+I) = RVOD2(I)
+C
+      DO 20 I = 1,LENIV1
+ 20     ISAV(I) = IVOD1(I)
+      DO 25 I = 1,LENIV2
+ 25     ISAV(LENIV1+I) = IVOD2(I)
+C
+      RETURN
+C
+ 100  CONTINUE
+      DO 110 I = 1,LENRV1
+ 110     RVOD1(I) = RSAV(I)
+      DO 115 I = 1,LENRV2
+ 115     RVOD2(I) = RSAV(LENRV1+I)
+C
+      DO 120 I = 1,LENIV1
+ 120     IVOD1(I) = ISAV(I)
+      DO 125 I = 1,LENIV2
+ 125     IVOD2(I) = ISAV(LENIV1+I)
+C
+      RETURN
+C----------------------- End of Subroutine ZVSRCO ----------------------
+      END
+*DECK ZEWSET
+      SUBROUTINE ZEWSET (N, ITOL, RTOL, ATOL, YCUR, EWT)
+C***BEGIN PROLOGUE  ZEWSET
+C***SUBSIDIARY
+C***PURPOSE  Set error weight vector.
+C***TYPE      DOUBLE PRECISION (SEWSET-S, DEWSET-D, ZEWSET-Z)
+C***AUTHOR  Hindmarsh, Alan C., (LLNL)
+C***DESCRIPTION
+C
+C  This subroutine sets the error weight vector EWT according to
+C      EWT(i) = RTOL(i)*ABS(YCUR(i)) + ATOL(i),  i = 1,...,N,
+C  with the subscript on RTOL and/or ATOL possibly replaced by 1 above,
+C  depending on the value of ITOL.
+C
+C***ROUTINES CALLED  (NONE)
+C***REVISION HISTORY  (YYMMDD)
+C   060502  DATE WRITTEN, modified from DEWSET of 930809.
+C***END PROLOGUE  ZEWSET
+      DOUBLE COMPLEX YCUR
+      DOUBLE PRECISION RTOL, ATOL, EWT
+      INTEGER N, ITOL
+      INTEGER I
+      DIMENSION RTOL(*), ATOL(*), YCUR(N), EWT(N)
+C
+C***FIRST EXECUTABLE STATEMENT  ZEWSET
+      GO TO (10, 20, 30, 40), ITOL
+ 10   CONTINUE
+      DO 15 I = 1,N
+ 15     EWT(I) = RTOL(1)*ABS(YCUR(I)) + ATOL(1)
+      RETURN
+ 20   CONTINUE
+      DO 25 I = 1,N
+ 25     EWT(I) = RTOL(1)*ABS(YCUR(I)) + ATOL(I)
+      RETURN
+ 30   CONTINUE
+      DO 35 I = 1,N
+ 35     EWT(I) = RTOL(I)*ABS(YCUR(I)) + ATOL(1)
+      RETURN
+ 40   CONTINUE
+      DO 45 I = 1,N
+ 45     EWT(I) = RTOL(I)*ABS(YCUR(I)) + ATOL(I)
+      RETURN
+C----------------------- END OF SUBROUTINE ZEWSET ----------------------
+      END
+*DECK ZVNORM
+      DOUBLE PRECISION FUNCTION ZVNORM (N, V, W)
+C***BEGIN PROLOGUE  ZVNORM
+C***SUBSIDIARY
+C***PURPOSE  Weighted root-mean-square vector norm.
+C***TYPE      DOUBLE COMPLEX (SVNORM-S, DVNORM-D, ZVNORM-Z)
+C***AUTHOR  Hindmarsh, Alan C., (LLNL)
+C***DESCRIPTION
+C
+C  This function routine computes the weighted root-mean-square norm
+C  of the vector of length N contained in the double complex array V,
+C  with weights contained in the array W of length N:
+C    ZVNORM = SQRT( (1/N) * SUM( abs(V(i))**2 * W(i)**2 )
+C  The squared absolute value abs(v)**2 is computed by ZABSSQ.
+C
+C***ROUTINES CALLED  ZABSSQ
+C***REVISION HISTORY  (YYMMDD)
+C   060502  DATE WRITTEN, modified from DVNORM of 930809.
+C***END PROLOGUE  ZVNORM
+      DOUBLE COMPLEX V
+      DOUBLE PRECISION W,   SUM, ZABSSQ
+      INTEGER N,   I
+      DIMENSION V(N), W(N)
+C
+C***FIRST EXECUTABLE STATEMENT  ZVNORM
+      SUM = 0.0D0
+      DO 10 I = 1,N
+ 10     SUM = SUM + ZABSSQ(V(I)) * W(I)**2
+      ZVNORM = SQRT(SUM/N)
+      RETURN
+C----------------------- END OF FUNCTION ZVNORM ------------------------
+      END
+*DECK ZABSSQ
+      DOUBLE PRECISION FUNCTION ZABSSQ(Z)
+C***BEGIN PROLOGUE  ZABSSQ
+C***SUBSIDIARY
+C***PURPOSE  Squared absolute value of a double complex number.
+C***TYPE      DOUBLE PRECISION (ZABSSQ-Z)
+C***AUTHOR  Hindmarsh, Alan C., (LLNL)
+C***DESCRIPTION
+C
+C  This function routine computes the square of the absolute value of
+C  a double precision complex number Z,
+C    ZABSSQ = DREAL(Z)**2 * DIMAG(Z)**2
+C***REVISION HISTORY  (YYMMDD)
+C   060502  DATE WRITTEN.
+C***END PROLOGUE  ZABSSQ
+      DOUBLE COMPLEX Z
+      ZABSSQ = DREAL(Z)**2 + DIMAG(Z)**2
+      RETURN
+C----------------------- END OF FUNCTION ZABSSQ ------------------------
+      END
+*DECK DZSCAL
+      SUBROUTINE DZSCAL(N, DA, ZX, INCX)
+C***BEGIN PROLOGUE  DZSCAL
+C***SUBSIDIARY
+C***PURPOSE  Scale a double complex vector by a double prec. constant.
+C***TYPE      DOUBLE PRECISION (DZSCAL-Z)
+C***AUTHOR  Hindmarsh, Alan C., (LLNL)
+C***DESCRIPTION
+C  Scales a double complex vector by a double precision constant.
+C  Minor modification of BLAS routine ZSCAL.
+C***REVISION HISTORY  (YYMMDD)
+C   060530  DATE WRITTEN.
+C***END PROLOGUE  DZSCAL
+      DOUBLE COMPLEX ZX(*)
+      DOUBLE PRECISION DA
+      INTEGER I,INCX,IX,N
+C
+      IF( N.LE.0 .OR. INCX.LE.0 )RETURN
+      IF(INCX.EQ.1)GO TO 20
+C Code for increment not equal to 1
+      IX = 1
+      DO 10 I = 1,N
+        ZX(IX) = DA*ZX(IX)
+        IX = IX + INCX
+   10 CONTINUE
+      RETURN
+C Code for increment equal to 1
+   20 DO 30 I = 1,N
+        ZX(I) = DA*ZX(I)
+   30 CONTINUE
+      RETURN
+      END
+*DECK DZAXPY
+      SUBROUTINE DZAXPY(N, DA, ZX, INCX, ZY, INCY)
+C***BEGIN PROLOGUE  DZAXPY
+C***PURPOSE  Real constant times a complex vector plus a complex vector.
+C***TYPE      DOUBLE PRECISION (DZAXPY-Z)
+C***AUTHOR  Hindmarsh, Alan C., (LLNL)
+C***DESCRIPTION
+C  Add a D.P. real constant times a complex vector to a complex vector.
+C  Minor modification of BLAS routine ZAXPY.
+C***REVISION HISTORY  (YYMMDD)
+C   060530  DATE WRITTEN.
+C***END PROLOGUE  DZAXPY
+      DOUBLE COMPLEX ZX(*),ZY(*)
+      DOUBLE PRECISION DA
+      INTEGER I,INCX,INCY,IX,IY,N
+      IF(N.LE.0)RETURN
+      IF (ABS(DA) .EQ. 0.0D0) RETURN
+      IF (INCX.EQ.1.AND.INCY.EQ.1)GO TO 20
+C Code for unequal increments or equal increments not equal to 1
+      IX = 1
+      IY = 1
+      IF(INCX.LT.0)IX = (-N+1)*INCX + 1
+      IF(INCY.LT.0)IY = (-N+1)*INCY + 1
+      DO 10 I = 1,N
+        ZY(IY) = ZY(IY) + DA*ZX(IX)
+        IX = IX + INCX
+        IY = IY + INCY
+   10 CONTINUE
+      RETURN
+C Code for both increments equal to 1
+   20 DO 30 I = 1,N
+        ZY(I) = ZY(I) + DA*ZX(I)
+   30 CONTINUE
+      RETURN
+      END
+*DECK DUMACH
+      DOUBLE PRECISION FUNCTION DUMACH ()
+C***BEGIN PROLOGUE  DUMACH
+C***PURPOSE  Compute the unit roundoff of the machine.
+C***CATEGORY  R1
+C***TYPE      DOUBLE PRECISION (RUMACH-S, DUMACH-D)
+C***KEYWORDS  MACHINE CONSTANTS
+C***AUTHOR  Hindmarsh, Alan C., (LLNL)
+C***DESCRIPTION
+C *Usage:
+C        DOUBLE PRECISION  A, DUMACH
+C        A = DUMACH()
+C
+C *Function Return Values:
+C     A : the unit roundoff of the machine.
+C
+C *Description:
+C     The unit roundoff is defined as the smallest positive machine
+C     number u such that  1.0 + u .ne. 1.0.  This is computed by DUMACH
+C     in a machine-independent manner.
+C
+C***REFERENCES  (NONE)
+C***ROUTINES CALLED  DUMSUM
+C***REVISION HISTORY  (YYYYMMDD)
+C   19930216  DATE WRITTEN
+C   19930818  Added SLATEC-format prologue.  (FNF)
+C   20030707  Added DUMSUM to force normal storage of COMP.  (ACH)
+C***END PROLOGUE  DUMACH
+C
+      DOUBLE PRECISION U, COMP
+C***FIRST EXECUTABLE STATEMENT  DUMACH
+      U = 1.0D0
+ 10   U = U*0.5D0
+      CALL DUMSUM(1.0D0, U, COMP)
+      IF (COMP .NE. 1.0D0) GO TO 10
+      DUMACH = U*2.0D0
+      RETURN
+C----------------------- End of Function DUMACH ------------------------
+      END
+      SUBROUTINE DUMSUM(A,B,C)
+C     Routine to force normal storing of A + B, for DUMACH.
+      DOUBLE PRECISION A, B, C
+      C = A + B
+      RETURN
+      END

Property changes on: trunk/scipy/integrate/odepack/zvode.f
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Name: svn:eol-style
+ native