Sets the scaling type for the inner inverse Jacobian in SNESQN.


#include "petscsnes.h" 
PetscErrorCode SNESQNSetScaleType(SNES snes, SNESQNScaleType stype)
Logically Collective on SNES

Input Parameters

snes - the iterative context
stype - scale type

Options Database

-snes_qn_scale_type <diagonal,none,scalar,jacobian>

Level: intermediate


SNES_QN_SCALE_NONE - don't scale the problem
SNES_QN_SCALE_SCALAR - use shanno scaling
SNES_QN_SCALE_DIAGONAL - scale with a diagonalized BFGS formula (see Gilbert and Lemarechal 1989), available
SNES_QN_SCALE_JACOBIAN - scale by solving a linear system coming from the Jacobian you provided with SNESSetJacobian() computed at the first iteration of QN and at ever restart.

See Also

SNES, SNESQN, SNESLineSearch, SNESQNScaleType, SNESetJacobian()