Re: ATLAS and octave

[John W. Eaton]

Here is all I did to build a copy of Octave that uses ATLAS:

  1. build ATLAS

  2. merge all four of the libraries that the ATLAS build creates into
     a single libatlas.a and install it in /some/dir.

  3. relink Octave by running

       make SPECIAL_MATH_LIB=/some/dir/libatlas.a

That seems to be all that is needed.

Would it be possible to modify the ATLAS makefiles to just build a
libatlas.a?  Then Octave could simply have

  AC_CHECK_LIB(atlas, ATL_xerbla)

in the configure script, and set SPECIAL_MATH_LIB accordingly.

Things might get a little more complicated for shared libraries.  Some
systems seem to barf when multiple shared libraries define the same
symbol.  But it would probably be possible to solve that, either by
doing whatever is necesary to tell the dynamic linker not to barf, or
by omitting the duplicate symbols from libcruft.

BTW, I see the following speedup on my system (266MHz Pentium II):

  octave:1> a = rand (1000); b = rand (1000); 
  octave:2> t = cputime (); a * b; cputime () - t

  without ATLAS:  94.4 seconds
  with ATLAS:     10.5 seconds

Wow!

Thanks,

jwe



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