question on MatMatMult

[Randall Mackie]

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