Thomas Weber wrote:
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?
The answer in my last mail was just a guess (I did not have access to
the same machine). Now, I was able to check this on a different machine.
Yes, I can confirm that the result depends on the fact whether atlas is
installed or not.
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.
Yes, I agree. Setting the dependences accordingly would solve the
problem for the debian users of octave.
Regards
Thomas
Regards,
Alois
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