PCLU#

Uses a direct solver, based on LU factorization, as a preconditioner

Options Database Keys#

  • -pc_factor_reuse_ordering - Activate PCFactorSetReuseOrdering()

  • -pc_factor_mat_solver_type - Actives PCFactorSetMatSolverType() to choose the direct solver, like superlu

  • -pc_factor_reuse_fill - Activates PCFactorSetReuseFill()

  • -pc_factor_fill - Sets fill amount

  • -pc_factor_in_place - Activates in-place factorization

  • -pc_factor_mat_ordering_type <nd,rcm,…> - Sets ordering routine

  • -pc_factor_pivot_in_blocks <true,false> - allow pivoting within the small blocks during factorization (may increase stability of factorization.

  • -pc_factor_shift_type - Sets shift type or -1 for the default; use ‘-help’ for a list of available types

  • -pc_factor_shift_amount - Sets shift amount or -1 for the default

  • -pc_factor_nonzeros_along_diagonal - permutes the rows and columns to try to put nonzero value along the diagonal.

  • -pc_factor_mat_solver_type - use an external package for the solve, see MatSolverType for possibilities

  • -mat_solvertype_optionname - options for a specific solver package, for example -mat_mumps_cntl_1

Notes#

Not all options work for all matrix formats

Run with -help to see additional options for particular matrix formats or factorization algorithms

Usually this will compute an “exact” solution in one iteration and does not need a Krylov method (i.e. you can use -ksp_type preonly, or KSPSetType(ksp,KSPPREONLY) for the Krylov method

See Also#

KSP: Linear System Solvers, PCCreate(), PCSetType(), PCType, PC, MatSolverType, MatGetFactor(), PCQR, PCSVD, PCILU, PCCHOLESKY, PCICC, PCFactorSetReuseOrdering(), PCFactorSetReuseFill(), PCFactorGetMatrix(), PCFactorSetFill(), PCFactorSetUseInPlace(), PCFactorSetMatOrderingType(), PCFactorSetColumnPivot(), PCFactorSetPivotInBlocks(), PCFactorSetShiftType(), PCFactorSetShiftAmount() PCFactorReorderForNonzeroDiagonal()

Level#

beginner

Location#

src/ksp/pc/impls/factor/lu/lu.c

Index of all PC routines
Table of Contents for all manual pages
Index of all manual pages