petsc-3.7.7 2017-09-25

PCSORSetSymmetric

Sets the SOR preconditioner to use symmetric (SSOR), backward, or forward relaxation. The local variants perform SOR on each processor. By default forward relaxation is used.

Synopsis

#include "petscpc.h" 
PetscErrorCode  PCSORSetSymmetric(PC pc,MatSORType flag)

Logically Collective on PC

Input Parameters

	pc	- the preconditioner context
	flag	- one of the following

    SOR_FORWARD_SWEEP
    SOR_BACKWARD_SWEEP
    SOR_SYMMETRIC_SWEEP
    SOR_LOCAL_FORWARD_SWEEP
    SOR_LOCAL_BACKWARD_SWEEP
    SOR_LOCAL_SYMMETRIC_SWEEP

Options Database Keys

	-pc_sor_symmetric	- Activates symmetric version
	-pc_sor_backward	- Activates backward version
	-pc_sor_local_forward	- Activates local forward version
	-pc_sor_local_symmetric	- Activates local symmetric version
	-pc_sor_local_backward	- Activates local backward version

Notes

To use the Eisenstat trick with SSOR, employ the PCEISENSTAT preconditioner, which can be chosen with the option

-pc_type eisenstat -Activates Eisenstat trick

Keywords

PC, SOR, SSOR, set, relaxation, sweep, forward, backward, symmetric

Examples

src/ksp/ksp/examples/tutorials/ex21f.F.html