PCFactorSetShiftPd

 specify whether to use Manteuffel shifting. If a matrix factorisation breaks down because of nonpositive pivots, adding sufficient identity to the diagonal will remedy this. Setting this causes a bisection method to find the minimum shift that will lead to a well-defined matrix factor.

Synopsis

#include "petscpc.h" 
PetscErrorCode PETSCKSP_DLLEXPORT PCFactorSetShiftPd(PC pc,PetscTruth shift)
Collective on PC

Input parameters

pc - the preconditioner context
shifting - PETSC_TRUE to set shift else PETSC_FALSE

Options Database Key

-pc_factor_shift_positive_definite [PETSC_TRUE/PETSC_FALSE] -Activate/Deactivate PCFactorSetShiftPd(); the value is optional with PETSC_TRUE being the default

Keywords

PC, indefinite, factorization

See Also

PCFactorSetZeroPivot(), PCFactorSetShiftNonzero()

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

Examples

src/ksp/pc/examples/tutorials/ex1.c.html