petsc-3.4.2 2013-07-02

# SNESQNSetRestartType

Sets the restart type for SNESQN.

### Synopsis

    #include "petscsnes.h"
    PetscErrorCode SNESQNSetRestartType(SNES snes, SNESQNRestartType rtype)

Logically Collective on SNES

### Input Parameters

| snes | - the iterative context
| rtype | - restart type

### Options Database

| -snes_qn_restart_type<powell,periodic,none> | - set the restart type
| -snes_qn_restart[10] | - sets the number of iterations before restart for periodic

### SNESQNRestartTypes

| SNES_QN_RESTART_NONE | - never restart
| SNES_QN_RESTART_POWELL | - restart based upon descent criteria
| SNES_QN_RESTART_PERIODIC | - restart after a fixed number of iterations

### Notes

The default line search used is the L2 line search and it requires two additional function evaluations.

### Keywords

SNES, SNESQN, restart, type, set SNESLineSearch

Level:intermediate
Location: src/snes/impls/qn/qn.c
Index of all SNES routines
Table of Contents for all manual pages
Index of all manual pages