SNESSetJacobian

Sets the function to compute Jacobian as well as the location to store the matrix.

Synopsis

#include "petscsnes.h"  
PetscErrorCode PETSCSNES_DLLEXPORT SNESSetJacobian(SNES snes,Mat A,Mat B,PetscErrorCode (*func)(SNES,Vec,Mat*,Mat*,MatStructure*,void*),void *ctx)
Collective on SNES and Mat

Input Parameters

snes - the SNES context
A - Jacobian matrix
B - preconditioner matrix (usually same as the Jacobian)
func - Jacobian evaluation routine
ctx - [optional] user-defined context for private data for the Jacobian evaluation routine (may be PETSC_NULL)

Calling sequence of func

    func (SNES snes,Vec x,Mat *A,Mat *B,int *flag,void *ctx);

x - input vector
A - Jacobian matrix
B - preconditioner matrix, usually the same as A
flag - flag indicating information about the preconditioner matrix structure (same as flag in KSPSetOperators()), one of SAME_NONZERO_PATTERN,DIFFERENT_NONZERO_PATTERN,SAME_PRECONDITIONER
ctx - [optional] user-defined Jacobian context

Notes

See KSPSetOperators() for important information about setting the flag output parameter in the routine func(). Be sure to read this information!

The routine func() takes Mat * as the matrix arguments rather than Mat. This allows the Jacobian evaluation routine to replace A and/or B with a completely new new matrix structure (not just different matrix elements) when appropriate, for instance, if the nonzero structure is changing throughout the global iterations.

If the A matrix and B matrix are different you must call MatAssemblyBegin/End() on each matrix.

Keywords

SNES, nonlinear, set, Jacobian, matrix

See Also

KSPSetOperators(), SNESSetFunction(), MatMFFDComputeJacobian(), SNESDefaultComputeJacobianColor(), MatStructure

Level:beginner
Location:
src/snes/interface/snes.c
Index of all SNES routines
Table of Contents for all manual pages
Index of all manual pages

Examples

src/snes/examples/tutorials/ex1.c.html
src/snes/examples/tutorials/ex2.c.html
src/snes/examples/tutorials/ex3.c.html
src/snes/examples/tutorials/ex5.c.html
src/snes/examples/tutorials/ex5s.c.html
src/snes/examples/tutorials/ex6.c.html
src/snes/examples/tutorials/ex14.c.html
src/snes/examples/tutorials/ex24.c.html
src/snes/examples/tutorials/ex26.c.html
src/snes/examples/tutorials/ex38.c.html
src/snes/examples/tutorials/ex42.c.html