Bug#419556: [Pkg-octave-devel] Bug#419556: ambigous results in matrix multipliication

[Thomas Weber]

Hi, 

Am Montag, 16. April 2007 17:32 schrieb Alois Schloegl:
> One expects that a matrix multiplication (A*B)' gives the same result than
> for (B'*A'). This is not the case for the debian octave package (tested
> with 2.9.10-3 and 2.1.73-13)
>
> Here is the test script:
>
> repmat(0,2)*repmat(NaN,2)
> repmat(NaN,2)*repmat(0,2)
> repmat(0,2)*repmat(inf,2)
> repmat(inf,2)*repmat(0,2)
> version
> octave_config_info('BLAS_LIBS')

I take it for granted that you didn't have ATLAS installed. Is this correct?

Unless I'm mistaken, the reference implementation of dgemm is supposed to do 
exactly this, see
http://velveeta.che.wisc.edu/octave/lists/bug-octave/2002/310

> The problem seems to be in the lapack or blas library. Because this problem
> disappears (the result is always NaN) when I compile Octave from the
> sources using Atlas. 

I guess the best "fix" for this problem is installing one of the atlas3-* 
packages.

Regards
	Thomas