petsc-3.12.5 2020-03-29

SNESSetFunction

Sets the function evaluation routine and function vector for use by the SNES routines in solving systems of nonlinear equations.

#include "petscsnes.h"  
PetscErrorCode  SNESSetFunction(SNES snes,Vec r,PetscErrorCode (*f)(SNES,Vec,Vec,void*),void *ctx)

Logically Collective on SNES

	snes	- the SNES context
	r	- vector to store function value
	f	- function evaluation routine; see SNESFunction for calling sequence details
	ctx	- [optional] user-defined context for private data for the function evaluation routine (may be NULL)

The Newton-like methods typically solve linear systems of the form

     f'(x) x = -f(x),

where f'(x) denotes the Jacobian matrix and f(x) is the function.

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