SNESPruneJacobianColor#

Remove nondiagonal zeros in the Jacobian matrix and update the MatMFFD coloring information based on the new nonzero structure

Synopsis#

#include "petscsnes.h"  
#include "petscdm.h"    
PetscErrorCode SNESPruneJacobianColor(SNES snes, Mat J, Mat B)

Collective

Input Parameters#

  • snes - the SNES context

  • J - Jacobian matrix (not altered in this routine)

  • B - newly computed Jacobian matrix to use with preconditioner (generally the same as J)

Notes#

This function improves the MatMFFD coloring performance when the Jacobian matrix is overallocated or contains many constant zeros entries, which is typically the case when the matrix is generated by a DM and multiple fields are involved.

Users need to make sure that the Jacobian matrix is properly filled to reflect the sparsity structure. For MatMFFD coloring, the values of nonzero entries are not important. So one can usually call SNESComputeJacobian() with randomized input vectors to generate a dummy Jacobian. SNESComputeJacobian() should be called before SNESSolve() but after SNESSetUp().

See Also#

SNES: Nonlinear Solvers, SNESComputeJacobianDefaultColor(), MatEliminateZeros(), MatFDColoringCreate(), MatFDColoringSetFunction()

Level#

intermediate

Location#

src/snes/interface/snesj2.c

Index of all SNES routines
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Index of all manual pages