Re: Octave and LAPACK

[Przemek Klosowski]

   A few times ago, I've posted about PCA calculations which results 
   differ between MacOSX and Linux Mandrake. I've continued the test with 
   octave and Matlab 7.01. Data and functions were the same for all the 
   trials :-)
   1. Octave 2.1.64 and MatLab 7.0.1 give the same results on each 
   machine. On Linux MDK 10.1, octave and matlab give the same results, on 
   MacOSX octave and matlab give the same results. But the results differ 
   from MacOSX and Linux MDK. I guess both octave and matlab use the host 
   operating system LAPACK libraries...
   2. Octave 2.1.64 on Linux MDK 10.1 and octave 2.1.57 on Debian woody 
   give slightly different results
   3. Octave 2.1.64 on last dev Debian running on opteron processor give a 
   result slightly different of the MacOSX one and different from the others.

Congratulations, you have performed a first-cut estimation of the
stability of the numerical algorithm that you use. Most people do not
do that, and report the results of their calculation as if it was an
exact number ("I got 3.1416"). You, on the other hand, can now say "I
got 3.1415 plus-minus 0.0001", which is what they would make you do
anyway if you tried to publish a paper around here :)

       p



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