petsc-3.7.1 2016-05-15
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# SNESSetJacobian

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

### Synopsis

    #include "petscsnes.h"
    PetscErrorCode  SNESSetJacobian(SNES snes,Mat Amat,Mat Pmat,PetscErrorCode (*J)(SNES,Vec,Mat,Mat,void*),void *ctx)

Logically Collective on SNES and Mat Many br

### Input Parameters

| snes | - the SNES context Many br
| Amat | - the matrix that defines the (approximate) Jacobian Many br
| Pmat | - the matrix to be used in constructing the preconditioner, usually the same as Amat. Many br
| J | - Jacobian evaluation routine (if NULL then SNES retains any previously set value), see SNESJacobianFunction for details Many br
| ctx | - [optional] user-defined context for private data for the Many brJacobian evaluation routine (may be NULL) (if NULL then SNES retains any previously set value) Many br

### Notes

If the Amat matrix and Pmat matrix are different you must call MatAssemblyBegin/End() on Many breach matrix. Many br

If you know the operator Amat has a null space you can use MatSetNullSpace() and MatSetTransposeNullSpace() to supply the null Many brspace to Amat and the KSP solvers will automatically use that null space as needed during the solution process. Many br

If using SNESComputeJacobianDefaultColor() to assemble a Jacobian, the ctx argument Many brmust be a MatFDColoring. Many br

Other defect-correction schemes can be used by computing a different matrix in place of the Jacobian. One common Many brexample is to use the "Picard linearization" which only differentiates through the highest order parts of each term. Many br

Many br

### Keywords

SNES, nonlinear, set, Jacobian, matrix

### See Also

KSPSetOperators(), SNESSetFunction(), MatMFFDComputeJacobian(), SNESComputeJacobianDefaultColor(), MatStructure, J,
SNESSetPicard(), SNESJacobianFunction Many br

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/ex5s.c.html
src/snes/examples/tutorials/ex12.c.html
src/snes/examples/tutorials/ex14.c.html
src/snes/examples/tutorials/ex15.c.html
src/snes/examples/tutorials/ex18.c.html
src/snes/examples/tutorials/ex20.c.html
src/snes/examples/tutorials/ex22.c.html
src/snes/examples/tutorials/ex28.c.html