Hello everyone.
I'm trying to solve a linear system (which comes from 3D FEM with
structured DM mesh) with a direct solver. I configured petsc installation
with mumps (–download-mumps –download-scalapack –download-parmetis
–download-metis, --download-hwloc, without ptscotch) and I have the
following functions:
// K is the stiffness matrix, assembly correctly
// U is the solution vector
// RHS is the right hand side of the linear equation
Mat Kfactor;
ierr = MatGetFactor(K,MATSOLVERMUMPS, MAT_FACTOR_CHOLESKY, &Kfactor);
CHKERRQ(ierr);
ierr = MatCholeskyFactorSymbolic(Kfactor,K,0,0); CHKERRQ(ierr);
ierr = MatCholeskyFactorNumeric(Kfactor,K,0); CHKERRQ(ierr);
ierr = MatSolve(Kfactor,RHS,U);
and run with options:
-pc_type cholesky -pc_factor_mat_solver_type mumps -mat_mumps_icntl_1 1
-mat_mumps_icntl_13 0 -mat_mumps_icntl_28 2 -mat_mumps_icntl_29 2
PROBLEM:
I got the correct solution, but the function MatCholeskyFactorNumeric( )
takes too much time to be completed. MatCholeskyFactorSymbolic() and
MatSolve() are very fast. The test uses a square K matrix of 700k dofs, and
the MatCholeskyFactorNumeric() takes around 14 minutes, while an iterative
solver (KSPCG/PCJACOBI) takes 5 seconds to get the solution. Any
suggestions?
Thanks in advance.
