PCICC

Incomplete Cholesky factorization preconditioners.

Options Database Keys

-pc_factor_levels <k> - number of levels of fill for ICC(k)
-pc_factor_in_place - only for ICC(0) with natural ordering, reuses the space of the matrix for its factorization (overwrites original matrix)
-pc_factor_fill <nfill> - expected amount of fill in factored matrix compared to original matrix, nfill > 1
-pc_factor_mat_ordering_type <natural,nd,1wd,rcm,qmd> - set the row/column ordering of the factored matrix
-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 parallel use you must use MATMPIROWBS, see MatCreateMPIRowbs(), this supports only ICC(0) and this is not recommended unless you really want a parallel ICC).

For BAIJ matrices this implements a point block ICC.

The Manteuffel shift is only implemented for matrices with block size 1

By default, the Manteuffel is applied (for matrices with block size 1). Call PCFactorSetShiftPd(pc,PETSC_FALSE); to turn off the shift.

References

Review article: APPROXIMATE AND INCOMPLETE FACTORIZATIONS, TONY F. CHAN AND HENK A. VAN DER VORST http://igitur-archive.library.uu.nl/math/2001-0621-115821/proc.pdf chapter in Parallel Numerical Algorithms, edited by D. Keyes, A. Semah, V. Venkatakrishnan, ICASE/LaRC Interdisciplinary Series in Science and Engineering, Kluwer, pp. 167--202.

See Also

PCCreate(), PCSetType(), PCType (for list of available types), PC, PCSOR, MatOrderingType,
PCFactorSetZeroPivot(), PCFactorSetShiftNonzero(), PCFactorSetShiftPd(), PCFactorSetFill(), PCFactorSetMatOrderingType(), PCFactorSetReuseOrdering(), PCFactorSetLevels(),PCFactorSetShiftNonzero(),PCFactorSetShiftPd(),

Level:beginner
Location:
src/ksp/pc/impls/factor/icc/icc.c
Index of all PC routines
Table of Contents for all manual pages
Index of all manual pages

Examples

src/ksp/pc/examples/tutorials/ex2.c.html