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

[Nils Wagner]

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
> 
>
>_______________________________________________
>SciPy-user mailing list
>SciPy-user at scipy.net
>http://www.scipy.net/mailman/listinfo/scipy-user
>  


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

-------------- next part --------------
A non-text attachment was scrubbed...
Name: test_inv.m
Type: application/m-file
Size: 46 bytes
Desc: not available
URL: <http://mail.scipy.org/pipermail/scipy-user/attachments/20051215/b9d0d19f/attachment.bin>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: test_inv.py
Type: text/x-python
Size: 107 bytes
Desc: not available
URL: <http://mail.scipy.org/pipermail/scipy-user/attachments/20051215/b9d0d19f/attachment.py>