Questions about Blas

[Barry Smith]

On Sep 16, 2009, at 2:09 PM, Rodrigo Araujo wrote:

> Thanks for the answer,
>
> But I have another question.
>
> I am trying to multiply the matrices using 2 pcs, so I found the  
> function MatMatMultNumeric_MPIDense_MPIDense, which probably could  
> do this using the BLAS. My question is how the BLAS or the MPI  
> splits the matrices to multiply them is separated pcs?

    This uses PLAPACK PLA_Gemm() which calls the BLAS appropriately.

    Barry

>
>
> 2009/9/16 Hong Zhang <hzhang at mcs.anl.gov>
>
> I am multiplying matrices using this line of code:
>
> ierr = MatMatMult(A, B, MAT_INITIAL_MATRIX, ((PetscReal) 2.0),
> &C);CHKERRQ(ierr);
>
> But I need to see the source code of the file which has this function,
> because I´d want to see how the functions from BLAS is being used.  
> Is that
> possible? If yes, could somebody tell me how.
>
> We have implementations for different matrix data structures.
> You can search 'MatMatMult_'
> from petsc/src/ for all.
> BLAS is used in MatMatMultNumeric_SeqDense_SeqDense()
> in src/mat/impls/dense/seq/dense.c.
> For sparse matrices, we do not use BLAS in MatMatMult().
>
> Hong
>
>
>
> -- 
> Rodrigo W. Pimentel Araujo
> Engenharia da Computação
> UFPE
>
>
>
> -- 
> Rodrigo W. Pimentel Araujo
> Engenharia da Computação
> UFPE