Satish Balay schrieb: > Not sure what you mean by "numbers of zero per row"
I actually meant "number of nonzeros per row", but providing the nnz[]-array to MatSeqAIJSetPreallocation brought only very little speed-up, by the same factor as preallocating just with nz. I suppose that I have to provide already the assembled sparse matrix to the PETSc-routines instead of calculating it element by element, as long as I don't distribute this calculation over many cpu's. cheers, ando > > Do you mean "number of zeros per row" or "column indices of zeros for > each row"?. Either way - you should be able to write a single loop > over this thingy - to compute the required nnz[] > > Satish > > On Thu, 23 Apr 2009, Andreas Grassl wrote: > >> Hello, >> >> I'm assembling large matrices giving just the numbers of zero per row and >> wondering if it is possible to extract the nonzero-structure in array-format >> it >> can be fed again into >> >> MatSeqAIJSetPreallocation(Mat B,PetscInt nz,const PetscInt nnz[]) >> >> to detect the bottleneck? >> >> cheers >> >> ando >> -- /"\ Grassl Andreas \ / ASCII Ribbon Campaign Uni Innsbruck Institut f. Mathematik X against HTML email Technikerstr. 13 Zi 709 / \ +43 (0)512 507 6091
