petsc-3.10.2 2018-10-09
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KSPLSQRSetExactMatNorm

Compute exact matrix norm instead of iteratively refined estimate.

Synopsis

#include "petscksp.h" 
PetscErrorCode  KSPLSQRSetExactMatNorm(KSP ksp, PetscBool flg)
Not Collective

Input Parameters

ksp - iterative context
flg - compute exact matrix norm or not

Notes

By default, flg=PETSC_FALSE. This is usually preferred to avoid possibly expensive computation of the norm. For flg=PETSC_TRUE, we call MatNorm(Amat,NORM_FROBENIUS,&lsqr->anorm) which will work only for some types of explicitly assembled matrices. This can affect convergence rate as KSPLSQRConvergedDefault() assumes different value of ||A|| used in normal equation stopping criterion.

Keywords

KSP, KSPLSQR

See Also

KSPSolve(), KSPLSQR, KSPLSQRGetNorms(), KSPLSQRConvergedDefault()

Level

intermediate

Location

src/ksp/ksp/impls/lsqr/lsqr.c
Index of all KSP routines
Table of Contents for all manual pages
Index of all manual pages