[Scipy-tickets] [SciPy] #1304: lobpcg fails on some machines for trivial problems

SciPy Trac scipy-tickets@scipy....
Wed Oct 13 15:29:55 CDT 2010


#1304: lobpcg fails on some machines for trivial problems
--------------------+-------------------------------------------------------
 Reporter:  nicki   |       Owner:  somebody
     Type:  defect  |      Status:  new     
 Priority:  normal  |   Milestone:  0.9.0   
Component:  Other   |     Version:  0.8.0   
 Keywords:          |  
--------------------+-------------------------------------------------------
 Hi,

 the attached code fails on my machine with

 ==================== *snip* ====================
 Solving generalized eigenvalue problem with preconditioning

 matrix size 5
 block size 1

 No constraints


 iteration 0
 [ True]
 current block size: 1
 eigenvalue: [ 25.]
 residual norms: [ 120.]
 iteration 1
 [ True]
 current block size: 1
 eigenvalue: [ 0.]
 residual norms: [  1.03680013e+09]
 iteration 2
 [ True]
 current block size: 1
 eigenvalue: [ 0.]
 residual norms: [  2.39610086e+45]
 iteration 3
 Warning: overflow encountered in multiply
 [ True]
 current block size: 1
 eigenvalue: [ 0.]
 residual norms: [ inf]
 Traceback (most recent call last):
   File "logpcg_test.py", line 8, in <module>
     lobpcg( A, X, verbosityLevel = 10 )
   File "/usr/lib64/python2.6/site-
 packages/scipy/sparse/linalg/eigen/lobpcg/lobpcg.py", line 391, in lobpcg
     aux = b_orthonormalize( B, activeBlockVectorR )
   File "/usr/lib64/python2.6/site-
 packages/scipy/sparse/linalg/eigen/lobpcg/lobpcg.py", line 130, in
 b_orthonormalize
     gramVBV = sla.cholesky( gramVBV )
   File "/usr/lib64/python2.6/site-
 packages/scipy/linalg/decomp_cholesky.py", line 66, in cholesky
     c, lower = _cholesky(a, lower=lower, overwrite_a=overwrite_a,
 clean=True)
   File "/usr/lib64/python2.6/site-
 packages/scipy/linalg/decomp_cholesky.py", line 16, in _cholesky
     a1 = asarray_chkfinite(a)
   File "/usr/lib64/python2.6/site-packages/numpy/lib/function_base.py",
 line 547, in asarray_chkfinite
     "array must not contain infs or NaNs")
 ValueError: array must not contain infs or NaNs
 ==================== *snap* ====================

 whereas on another one, one receives the expected output

 ==================== *snip* ====================
 Solving generalized eigenvalue problem with preconditioning

 matrix size 5
 block size 1

 No constraints


 iteration 0
 [False]
 final eigenvalue: [ 1.]
 final residual norms: [ 0.]
 ==================== *snap* ====================

 Cheers,
 Nico

-- 
Ticket URL: <http://projects.scipy.org/scipy/ticket/1304>
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