UMFPACK with ignore-nodes has very poor performance
Hi! I encountered a problem using the UMFPACK wrapper in dune-solvers. I noticed the poor performance of the UMFPACK solver is almost completely caused by the matrix copy process if there are ignore nodes involved.
I attached a demo file that demonstrates the issue.
It sets up a unit matrix of size 1e5 times 1e5 and solves the trivial system. One time, I set (empty) ignore nodes and the other time the system was solved without ignore nodes. The output is
UMFPACK with ignore nodes takes 84.4774 seconds
UMFPACK without ignore nodes takes 0.0172512 seconds
Edited by Patrick Jaap