question on MatMatMult

Randall Mackie rlmackie862 at
Mon Mar 17 17:28:35 CDT 2008

If I want to compute H = L^T L where L is a sparse matrix which is an approximation to the
laplacian, and hence H is the biharmonic (also sparse), and if I have L as an MPI matrix
in PETSc, will MatMatMult work for this (assuming I create the transpose of L first).

In other words, does MatMatMult look at the non-zero structure only that would result,
or does it think the result is a dense matrix?

Thanks, Randy

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