On 09/17/2012 01:33 PM, Roy Stogner wrote: > On Mon, 17 Sep 2012, John Peterson wrote: > >> On Mon, Sep 17, 2012 at 8:42 AM, Andrew E Slaughter >> <[email protected]> wrote: >>> I need to multiply two SparseMatrix objects together, in parallel, does >>> libMesh have this functionality? >>> >>> One possible solution is to use the PETSc MatMatMult function, but this >>> requires that I use PetscMatrix objects, which I also cannot figure out how >>> to do. Can someone indicate how I can specify the ImplicitSystem::matrix >>> and a matrix added with ImplicitSystem::add_matrix can be PetscMatrix >>> objects. >> I guess one question is what are you planning to do with the resulting >> matrix? >> >> In general it will have different sparsity than either of the two operands. > That's good to keep in mind. PETSc performance (at least in the older > versions where I've made this mistake) becomes atrocious if it's asked > to create new non-zero matrix entries on the fly without > preallocation.
Presumably MatMatMult in PETSc (or the equivalent in trilinos) handles this in some sensible way though. ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Libmesh-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/libmesh-users
