combined ATLAS/LAPACK library

[mmiranda]

Hi there,

I have a really basic question. If I build LAPACK with the reference BLAS (the one that comes with it), can I afterwards combine the built LAPACK with ATLAS or do I have to build LAPACK with ATLAS from the start?

The instructions in the ATLAS readme file say: "First, obtain the LAPACK src from netlib and build the LAPACK library as normal"

When they say "as normal", do they mean "build LAPACK with the reference BLAS"? Does it make any difference?

Any help would be appreciated.

Manuel

[Julien Langou]

hello,

when you build LAPACK "as normal", you should get two libraries,
one is named lapack_LINUX.a and the other one is blas_LINUX.a.

To compile an executable you need to link with the two libraries:
LAPACK and BLAS. However the BLAS libraries can be the reference
BLAS library (provided in LAPACK: blas_LINUX.a) but can also be any
other BLAS libraries.

So you can for example link with lapack_LINUX.a and atlas.

There are more information in other threads in the forum.

-j

[mmiranda]

Thanks for your quick reply Julien,

I'm a newbie to this topic so if I understood correctly:

1) If I bulid LAPACK using the reference BLAS that comes with it I will obtain lapack_LINUX.a and blas_LINUX.a. I will throw away blas_LINUX.a.

2) I will combine lapack_LINUX.a (just created) with lapack.a that comes with ATLAS (already compiled by the ATLAS folks). I will call this new combined library lapack.a.

3) Whenever I want to run something, I will link against ATLAS and my lapack.a.

So I guess it makes no difference whether I build LAPACK with ATLAS or with the reference BLAS, as long as when I build my own programs I link them with ATLAS. Am I correct?

Thanks,

Manuel

[Julien Langou]

kind of correct.
Step (2) is well explained on the ATLAS webpage but is not trivial.
Good luck
-j