MatSetNearNullSpace#

attaches a null space to a matrix, which is often the null space (rigid body modes) of the operator without boundary conditions This null space will be used to provide near null space vectors to a multigrid preconditioner built from this matrix.

Synopsis#

#include "petscmat.h" 
PetscErrorCode MatSetNearNullSpace(Mat mat, MatNullSpace nullsp)

Logically Collective on mat

Input Parameters#

  • mat - the matrix

  • nullsp - the null space object

Notes#

Overwrites any previous near null space that may have been attached

You can remove the null space by calling this routine with an nullsp of NULL

See Also#

MatNullSpace, MatCreate(), MatNullSpaceCreate(), MatSetNullSpace(), MatNullSpaceCreateRigidBody(), MatGetNearNullSpace()

Level#

advanced

Location#

src/mat/interface/matrix.c

Examples#

src/ksp/ksp/tutorials/ex49.c.html
src/ksp/ksp/tutorials/ex56.c.html
src/ksp/ksp/tutorials/ex59.c.html
src/ksp/ksp/tutorials/ex71.c.html
src/ksp/ksp/tutorials/ex72.c.html
src/snes/tutorials/ex56.c.html


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