petsc-3.13.6 2020-09-29

SNESCreate

Creates a nonlinear solver context.

Synopsis

#include "petscsnes.h"  
PetscErrorCode  SNESCreate(MPI_Comm comm,SNES *outsnes)

Collective

Input Parameters

comm -MPI communicator

Output Parameter

outsnes -the new SNES context

Options Database Keys

	-snes_mf	- Activates default matrix-free Jacobian-vector products, and no preconditioning matrix
	-snes_mf_operator	- Activates default matrix-free Jacobian-vector products, and a user-provided preconditioning matrix as set by SNESSetJacobian()
	-snes_fd	- Uses (slow!) finite differences to compute Jacobian

Developer Notes

SNES always creates a KSP object even though many SNES methods do not use it. This is unfortunate and should be fixed at some point. The flag snes->usesksp indicates if the particular method does use KSP and regulates if the information about the KSP is printed in SNESView(). TSSetFromOptions() does call SNESSetFromOptions() which can lead to users being confused by help messages about meaningless SNES options.

SNES always creates the snes->kspconvctx even though it is used by only one type. This should be fixed.

Level

beginner

SNESCreate

Synopsis

Input Parameters

Output Parameter

Options Database Keys

Developer Notes

See Also

Level

Location

Examples

Implementations