Re: Octave/C++ matrix Inv() comparison

[John W. Eaton]

On 07/09/2013 09:31 AM, ionone wrote:
> Thanks you
>
> I tried both *dgetrf/dgetri* and *dsytrf/dsytri* to inverse my matrix
> but i still have differences between Lapack and Octave. For example in
> Octave i have : *1.7338e+010* and with *dgetrf/dgetri* i have :
> *17351976742.876453* and with *dsytrf/dsytri* i have :
> *17352023489.128361* so you see they differ quite a lot...
>
> Do you have an idea what is the Inv() function of Octave in Lapack's
> formaty ? i tried to look into the code but i couldn't find anything
> relevant.

You can start by reading the inv.cc file.  I'm a bit surprised that it 
is hard to find that file and trace what the inv function does from 
there.  Anyway, for dense real-valued matrices, it ultimately calls the 
Matrix::inverse function defined in dMatrix.cc.

In any case, this is really the wrong list for this question.  The 
maintainers list is intended to be a place for discussion about the 
future development of Octave, not for questions about how to use Octave. 
 Could you please move this discussion to the help list?

Thanks,

jwe