petsc3.14.0 20200929
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
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