The PETSc built-in direct solver is slow for large systems. It really there for cases where LU is needed as part of another algorithm, e.g. the coarse level is multigrid.
If you want to solve large systems, use one of the specialised direct solvers. Garth On Sunday, 1 March 2015, Miro Kuchta <[email protected]> wrote: > Hi, > > please consider the attached script. Following this > <https://bitbucket.org/fenics-project/dolfin/pull-request/2/use-cholesky-rather-than-lu-decomposition/diff#chg-dolfin/fem/LinearVariationalSolver.cpp> > discussion, if method is mumps, petsc or pastix and > we have symmetric=True the linear system is solved with Cholesky > factorization (it this so?). While testing different method/symmetry > combinations I noticed that PETSc's own symmetric solver is easily > 10 times slower then mumps (I don't have pastix to compare against). Can > anyone else reproduce > this? Thanks. > > Regards, Miro > -- Garth N. Wells Department of Engineering, University of Cambridge http://www.eng.cam.ac.uk/~gnw20
_______________________________________________ fenics mailing list [email protected] http://fenicsproject.org/mailman/listinfo/fenics
