:: Actually I'm using an iterative method to solve Ax = b, and I guess it's simple, because I only need to do matrix vector multiplications in these methods ( e . g ., conjugate gradient, GMRES ).
12.
Due to the ubiquity of matrix multiplications in many scientific applications, including for the implementation of the rest of Level 3 BLAS, and because faster algorithms exist beyond the obvious repetition of matrix-vector multiplication, gemm is a prime target of optimization for BLAS implementers.
13.
The little research that has been done on this feature indicates that it may not be trivial to get high performance gains by using MPI-IO . For example, an implementation of sparse matrix-vector multiplications using the MPI I / O library shows a general behaviour of negligible performance gain, but these results are inconclusive.
