petsc-3.8.4 2018-03-24

MatGalerkin

Constructs the coarse grid problem via Galerkin projection.

Synopsis

#include "petscmat.h" 
PetscErrorCode  MatGalerkin(Mat restrct, Mat dA, Mat interpolate, MatReuse reuse, PetscReal fill, Mat *A)

If the interpolation and restriction operators are the same, uses MatPtAP. If they are not the same, use MatMatMatMult.

Once the coarse grid problem is constructed, correct for interpolation operators that are not of full rank, which can legitimately happen in the case of non-nested geometric multigrid.

Input Parameters

	restrct	- restriction operator
	dA	- fine grid matrix
	interpolate	- interpolation operator
	reuse	- either MAT_INITIAL_MATRIX or MAT_REUSE_MATRIX
	fill	- expected fill, use PETSC_DEFAULT if you do not have a good estimate

Output Parameters

A -the Galerkin coarse matrix

Options Database Key

-pc_mg_galerkin <both,pmat,mat,none> -

Keywords