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.

See Also#

KSP: Linear System Solvers, KSPSolve(), KSPLSQR, KSPLSQRGetNorms(), KSPLSQRConvergedDefault()

Level#

intermediate

Location#

src/ksp/ksp/impls/lsqr/lsqr.c


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