[SciPy-dev] Scipy cannot handle singular eigenvalue problems

Nils Wagner nwagner at mecha.uni-stuttgart.de
Wed Dec 10 03:14:46 CST 2003


Hi all,

Scipy cannot handle singular eigenvalue problems. Note, that both
matrices
are singular.

from scipy import *
A = array(([1.,-1.],[-1.,1.]))
B = array(([1.0,0.0],[0.0,0.0]))
w,vr = linalg.eig(A,B)
print w
print vr

Traceback (most recent call last):
  File "sevp.py", line 4, in ?
    w,vr = linalg.eig(A,B)
  File "/usr/lib/python2.3/site-packages/scipy/linalg/decomp.py", line
109, in eig
    return _geneig(a1,b,left,right,overwrite_a,overwrite_b)
  File "/usr/lib/python2.3/site-packages/scipy/linalg/decomp.py", line
68, in _geneig
    vr = _make_complex_eigvecs(w, vr, t)
  File "/usr/lib/python2.3/site-packages/scipy/linalg/decomp.py", line
29, in _make_complex_eigvecs
    vnew.real = scipy_base.take(vin,ind[::2],1)
ValueError: matrices are not aligned for copy

Any suggestion ?

The output of MATLAB is enclosed as well (out.ps)

Nils
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