petsc-3.12.5 2020-03-29

KSPSetTolerances

Sets the relative, absolute, divergence, and maximum iteration tolerances used by the default KSP convergence testers.

Synopsis

#include "petscksp.h" 
PetscErrorCode  KSPSetTolerances(KSP ksp,PetscReal rtol,PetscReal abstol,PetscReal dtol,PetscInt maxits)

Logically Collective on ksp

Input Parameters

	ksp	- the Krylov subspace context
	rtol	- the relative convergence tolerance, relative decrease in the (possibly preconditioned) residual norm
	abstol	- the absolute convergence tolerance absolute size of the (possibly preconditioned) residual norm
	dtol	- the divergence tolerance, amount (possibly preconditioned) residual norm can increase before KSPConvergedDefault() concludes that the method is diverging
	maxits	- maximum number of iterations to use

Options Database Keys

	-ksp_atol <abstol>	- Sets abstol
	-ksp_rtol <rtol>	- Sets rtol
	-ksp_divtol <dtol>	- Sets dtol
	-ksp_max_it <maxits>	- Sets maxits

Notes

Use PETSC_DEFAULT to retain the default value of any of the tolerances.

See KSPConvergedDefault() for details how these parameters are used in the default convergence test. See also KSPSetConvergenceTest() for setting user-defined stopping criteria.

convergence, maximum, iterations

Level

intermediate

Location

src/ksp/ksp/interface/itfunc.c

Examples