# MatPBRelax

Computes relaxation (SOR, Gauss-Seidel) sweeps.
### Synopsis

#include "petscmat.h"
PetscErrorCode PETSCMAT_DLLEXPORT MatPBRelax(Mat mat,Vec b,PetscReal omega,MatSORType flag,PetscReal shift,PetscInt its,PetscInt lits,Vec x)

Collective on Mat and Vec
See MatRelax() for usage

For multi-component PDEs where the Jacobian is stored in a point block format
(with the PETSc BAIJ matrix formats) the relaxation is done one point block at
a time. That is, the small (for example, 4 by 4) blocks along the diagonal are solved
simultaneously (that is a 4 by 4 linear solve is done) to update all the values at a point.

**Level:**developer

Location:src/mat/interface/matrix.c

Index of all Mat routines

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