[SciPy-dev] Possibly bug in logm

Nils Wagner nwagner at mecha.uni-stuttgart.de
Fri Oct 28 01:26:18 CDT 2005


>>> linalg.logm(1.0*identity(2))
array([[  0.00000000e+000,  -5.28723020e-270],
       [  0.00000000e+000,   0.00000000e+000]])
>>> linalg.logm(1.0*identity(2))
array([[  0.00000000e+000,   1.03655723e-269],
       [  0.00000000e+000,   0.00000000e+000]])
>>> linalg.logm(1.0*identity(2))
array([[ 0.,  0.],
       [ 0.,  0.]])
>>> linalg.logm(1.0*identity(2))
array([[  0.00000000e+000,   1.54221980e-269],
       [  0.00000000e+000,   0.00000000e+000]])
>>> linalg.logm(1.0*identity(2))
array([[ 0.,  0.],
       [ 0.,  0.]])
>>> linalg.logm(1.0*identity(2))
array([[ 0.,  0.],
       [ 0.,  0.]])
>>> linalg.logm(1.0*identity(2))
array([[  0.00000000e+000,  -9.25299312e-270],
       [  0.00000000e+000,   0.00000000e+000]])
>>> linalg.logm(1.0*identity(2))
array([[ 0.,  0.],
       [ 0.,  0.]])
>>> linalg.logm(1.0*identity(2))
array([[ 0.,  0.],
       [ 0.,  0.]])
>>> linalg.logm(1.0*identity(2))
array([[  0.00000000e+000,  -1.01171794e-269],
       [  0.00000000e+000,   0.00000000e+000]])
>>> linalg.logm(1.0*identity(2))
array([[ 0. +0.00000000e+00j,  0. +6.80000020e+01j],
       [ 0. +0.00000000e+00j,  0. +0.00000000e+00j]])
>>> linalg.logm(1.0*identity(2))
array([[ 0.,  0.],
       [ 0.,  0.]])
>>> linalg.logm(1.0*identity(2))
array([[ 0. +0.00000000e+00j,  0. -9.91687036e+00j],
       [ 0. +0.00000000e+00j,  0. +0.00000000e+00j]])

The repeated computation of logm() yields strange results.
Can someone reproduce this behaviour with latest svn versions ?

Nils






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