SNESSetUseMatrixFree#

indicates that SNES should use matrix-free finite difference matrix-vector products to apply the Jacobian.

Synopsis#

#include "petscsnes.h"  
PetscErrorCode SNESSetUseMatrixFree(SNES snes, PetscBool mf_operator, PetscBool mf)

Logically Collective

Input Parameters#

  • snes - SNES context

  • mf_operator - use matrix-free only for the Amat used by SNESSetJacobian(), this means the user provided Pmat will continue to be used

  • mf - use matrix-free for both the Amat and Pmat used by SNESSetJacobian(), both the Amat and Pmat set in SNESSetJacobian() will be ignored. With this option no matrix-element based preconditioners can be used in the linear solve since the matrix won’t be explicitly available

Options Database Keys#

  • -snes_mf_operator - use matrix-free only for the mat operator

  • -snes_mf - use matrix-free for both the mat and pmat operator

  • -snes_fd_color - compute the Jacobian via coloring and finite differences.

  • -snes_fd - compute the Jacobian via finite differences (slow)

Note#

SNES supports three approaches for computing (approximate) Jacobians: user provided via SNESSetJacobian(), matrix-free using MatCreateSNESMF(), and computing explicitly with finite differences and coloring using MatFDColoring. It is also possible to use automatic differentiation and the MatFDColoring object.

See Also#

SNES: Nonlinear Solvers, SNES, SNESGetUseMatrixFree(), MatCreateSNESMF(), SNESComputeJacobianDefaultColor(), MatFDColoring

Level#

intermediate

Location#

src/snes/interface/snes.c

Index of all SNES routines
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Index of all manual pages