Jed : New implementation for seqaij is in branch hzhang/opt-mattransposematmult. petsc/src/mat/examples/tests/ex209.c is a test. Please give it a try and let me know if you have any comment. I'll remove previous implementation and optimize MatTransposeMatMult() for mpiaij matrices. Hong Hong <[email protected]> writes:

...

It was implemented a decade ago for small to medium matrices. Your matrix structure reveals the worst part of outer product.

After discussing it with Barry, we decided to replace the algorithm (not API) using At=A^T and C=At*B for sequential implementation. In parallel, I'll do local MatTranspose (used for PtAP). I'll give you this new implementation in few days.

Perfect, thanks!