Incomplete factorization preconditioners.

Options Database Keys

-pc_factor_levels <k> - number of levels of fill for ILU(k)
-pc_factor_in_place - only for ILU(0) with natural ordering, reuses the space of the matrix for its factorization (overwrites original matrix)
-pc_factor_diagonal_fill - fill in a zero diagonal even if levels of fill indicate it wouldn't be fill
-pc_factor_reuse_ordering - reuse ordering of factorized matrix from previous factorization
-pc_factor_use_drop_tolerance <dt,dtcol,maxrowcount> - use Saad's drop tolerance ILUdt
-pc_factor_fill <nfill> - expected amount of fill in factored matrix compared to original matrix, nfill > 1
-pc_factor_nonzeros_along_diagonal - reorder the matrix before factorization to remove zeros from the diagonal, this decreases the chance of getting a zero pivot
-pc_factor_mat_ordering_type <natural,nd,1wd,rcm,qmd> - set the row/column ordering of the factored matrix
-pc_factor_pivot_in_blocks - for block ILU(k) factorization, i.e. with BAIJ matrices with block size larger than 1 the diagonal blocks are factored with partial pivoting (this increases the stability of the ILU factorization
-pc_factor_shift_nonzero <shift> - Sets shift amount or PETSC_DECIDE for the default
-pc_factor_shift_positive_definite [PETSC_TRUE/PETSC_FALSE] - Activate/Deactivate PCFactorSetShiftPd(); the value is optional with PETSC_TRUE being the default

Notes: Only implemented for some matrix formats. Not implemented in parallel

For BAIJ matrices this implements a point block ILU

See Also

PCCreate(), PCSetType(), PCType (for list of available types), PC, PCSOR, MatOrderingType,
PCFactorSetZeroPivot(), PCFactorSetShiftNonzero(), PCFactorSetShiftPd(), PCFactorSetUseDropTolerance(), PCFactorSetFill(), PCFactorSetMatOrdering(), PCFactorSetReuseOrdering(), PCFactorSetLevels(), PCFactorSetUseInPlace(), PCFactorSetAllowDiagonalFill(), PCFactorSetPivotInBlocks(), PCFactorSetShiftNonzero(),PCFactorSetShiftPd()

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