[Trilinos-Users] Why isn't BLAS used more in Epetra?

[Sven Baars]

Hey everyone,

I was wondering why BLAS isn't used more often. It seems to me that
you'd want to use this as much as possible. For instance in the Update
method of the Epetra_MultiVector. I attached an example where I test its
performance. Here is my output on my local machine:

$ ./test
Time with Update 1.35864
Time with daxpy_ 1.05639

and it's even threaded:

$ OMP_NUM_THREADS=4 ./test
Time with Update 1.38495
Time with daxpy_ 0.66636

Note that I don't compile Epetra with OpenMP support, because for me
it's bugged in some places. But I can't imagine that the implementation
in Epetra is better than the BLAS one. So why isn't BLAS used more often?

Cheers,
Sven

P.S. I know Teuchos has BLAS wrappers, but I just wanted to make sure I
was actually using BLAS, and that Tpetra probably does this better, but
Tpetra's API is still too unstable for me.
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