KSPLSQRGetNorms#
Get the norm estimates that KSPLSQR computes internally during KSPSolve().
Synopsis#
#include "petscksp.h"
PetscErrorCode KSPLSQRGetNorms(KSP ksp, PetscReal *arnorm, PetscReal *anorm)
Not Collective
Input Parameter#
ksp - iterative context
Output Parameters#
arnorm - good estimate of norm((A*inv(Pmat))’r), where r = Ax - b, used in specific stopping criterion
anorm - poor estimate of norm(A*inv(Pmat),’fro’) used in specific stopping criterion
Notes#
Output parameters are meaningful only after KSPSolve().
These are the same quantities as normar and norma in MATLAB’s lsqr(), whose output lsvec is a vector of normar / norma for all iterations.
If -ksp_lsqr_exact_mat_norm is set or KSPLSQRSetExactMatNorm(ksp, PETSC_TRUE) called, then anorm is the exact Frobenius norm.
See Also#
KSP: Linear System Solvers, KSPSolve(), KSPLSQR, KSPLSQRSetExactMatNorm()
Level#
intermediate
Location#
Index of all KSP routines
Table of Contents for all manual pages
Index of all manual pages