On 3/10/22 07:00, Hermes Sampedro wrote:
I am experiencing long computational times with the solver function. I am
trying to use DoFRenumbering::Cuthill_McKee(dof_handler),
DoFRenumbering::boost::Cuthill_McKee(dof_handler,false,false)
but I get even higher computational times. Am I doing something wrong?
Renumbering makes an enormous difference for sparse direct solvers, and as a
consequence all such solvers I know of do it internally (though they use
variations of the "minimum degree" renumbering, rather than Cuthill-McKee). As
a consequence, renumbering yourself likely makes no difference.
But, as you discover and as Bruno already pointed out, even with optimal
ordering, direct solvers do not scale well both in terms of overall time and
in parallelism. You may want to take a look at the several video lectures on
solvers and preconditioners to see what you can do about your case.
Best
W.
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Wolfgang Bangerth email: [email protected]
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