petsc-3.14.6 2021-03-30

KSPRichardsonSetSelfScale

Sets Richardson to automatically determine optimal scaling at each iteration to minimize the 2-norm of the preconditioned residual

#include "petscksp.h" 
PetscErrorCode  KSPRichardsonSetSelfScale(KSP ksp,PetscBool scale)

Logically Collective on ksp

	ksp	- the iterative context
	scale	- PETSC_TRUE or the default of PETSC_FALSE

-ksp_richardson_self_scale

- Use self-scaling

Requires two extra work vectors. Uses an extra VecAXPY() and VecDotNorm2() per iteration.

Could also minimize the 2-norm of the true residual with one less work vector

intermediate