[SciPy-user] Bug in inverse matrix calculation for "scipy_core-0.8.4.win32-py2.3.exe"

Nils Wagner nwagner at mecha.uni-stuttgart.de
Thu Dec 15 03:06:36 CST 2005


Travis Oliphant wrote:
>Randewijk P-J <pjrandew at sun.ac.za> wrote:
>
>  
>>Dear Travis,
>> 
>>Thank-you for the "silent" version (0.8.4) of scipy_core.
>> 
>>Unfortunately when trying to invert a singular matrix using scipy_core 
>>0.8.4, python "crashes" instead of issuing the usual error message:
>>    
>
>I'm not seeing this. I'm getting the proper error message.  Can you show 
>us the matrix you are using and give more information about the platform.
>
>Also, try it when the environment variable NO_SCIPY_IMPORT=1
>
>import os
>os.environ['NO_SCIPY_IMPORT']=1  # this will not import full scipy but 
>use only scipy_core\
>import scipy
>
>Full scipy installs its own (hopefully better) matrix inverse.  We need 
>to figure out which one is giving you trouble.
>
>-Travis
> 
>
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>  


Hi Travis,

I would prefer a warning similar to matlab

Warning: Matrix is close to singular or badly scaled.
Results may be inaccurate. e.g. RCOND=2.051286e-16

The inverse is useless in case of (nearly) singular matrices
and should not be used for further computations.

Any comments ?

Nils

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