Questions about Blas

Hong Zhang hzhang at
Wed Sep 16 09:56:30 CDT 2009

> 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().

> -- 
> Rodrigo W. Pimentel Araujo
> Engenharia da Computação

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