[SciPy-User] f2py: questions on array arguments

Ramon Crehuet rcsqtc@iqac.csic...
Tue Jun 29 06:03:51 CDT 2010


Dear all,
I have a couple of question on f2py.
1. The follwing fortran function:

function f2(x,y)
  implicit none
  real,intent(in):: x,y
  real, dimension(3):: f2
  f2(1)=x+y**2
  f2(2)=sin(x*y)
  f2(3)=2*x-y
end function f2

gives a segmentation fault when called from python if it is not in a
fortran module. If it is contained in a fortran module, it works fine
and returns an array. That makes sense because fortran modules
automatically generate an interface. However, I don't see that reflected
in the .pyf files generated by f2py. So, is there a way to "correct" the
function outside the module to work with f2py?

2. I have read in several posts that automatic arrays do not work with
f2py. So that something like:

real function trace(m)
  real, dimension(:,:), intent(in) :: m

Has to be converted into:

real function trace2(m,n)
  integer, intent(in) :: n
!f2py integer,intent(hide),depend(m) :: n=shape(m,0)
  real, dimension(n,n), intent(in) :: m

which works fine with f2py but is not nice in fortran. I've tried to do
something like:

real function trace(m)
!f2py integer,depend(m) :: n=shape(m,0)
!f2py real, dimension(n,n), intent(in) :: m
  real, dimension(:,:), intent(in) :: m

But it does not work. Is there a workaround to avoid passing the
dimension of the matrix as a fortran argument?

Thanks in advance!
Ramon





More information about the SciPy-User mailing list