KSPSetFromOptions#
Sets KSP
options from the options database. This routine must be called before KSPSetUp()
if the user is to be allowed to set the Krylov type.
Synopsis#
#include "petscksp.h"
PetscErrorCode KSPSetFromOptions(KSP ksp)
Collective
Input Parameter#
ksp - the Krylov space context
Options Database Keys#
-ksp_max_it - maximum number of linear iterations
-ksp_rtol rtol - relative tolerance used in default determination of convergence, i.e. if residual norm decreases by this factor than convergence is declared
-ksp_atol abstol - absolute tolerance used in default convergence test, i.e. if residual norm is less than this then convergence is declared
-ksp_divtol tol - if residual norm increases by this factor than divergence is declared
-ksp_converged_use_initial_residual_norm - see
KSPConvergedDefaultSetUIRNorm()
-ksp_converged_use_min_initial_residual_norm - see
KSPConvergedDefaultSetUMIRNorm()
-ksp_converged_maxits - see
KSPConvergedDefaultSetConvergedMaxits()
-ksp_norm_type - none - skip norms used in convergence tests (useful only when not using convergence test (say you always want to run with 5 iterations) to save on communication overhead preconditioned - default for left preconditioning unpreconditioned - see
KSPSetNormType()
natural - seeKSPSetNormType()
-ksp_check_norm_iteration it - do not compute residual norm until iteration number it (does compute at 0th iteration) works only for
KSPBCGS
,KSPIBCGS
and andKSPCG
-ksp_lag_norm - compute the norm of the residual for the ith iteration on the i+1 iteration; this means that one can use the norm of the residual for convergence test WITHOUT an extra
MPI_Allreduce()
limiting global synchronizations. This will require 1 more iteration of the solver than usual.-ksp_guess_type - Type of initial guess generator for repeated linear solves
-ksp_fischer_guess <model,size> - uses the Fischer initial guess generator for repeated linear solves
-ksp_constant_null_space - assume the operator (matrix) has the constant vector in its null space
-ksp_test_null_space - tests the null space set with
MatSetNullSpace()
to see if it truly is a null space-ksp_knoll - compute initial guess by applying the preconditioner to the right hand side
-ksp_monitor_cancel - cancel all previous convergene monitor routines set
-ksp_monitor - print residual norm at each iteration
-ksp_monitor draw::draw_lg - plot residual norm at each iteration
-ksp_monitor_true_residual - print true residual norm at each iteration
-all_ksp_monitor
- print residual norm at each iteration for ALL KSP solves, regardless of their prefix. This is useful forPCFIELDSPLIT
,PCMG
, etc that have inner solvers and you wish to track the convergence of all the solvers-ksp_monitor_solution [ascii binary or draw][:filename][:format option] - plot solution at each iteration
-ksp_monitor_singular_value - monitor extreme singular values at each iteration
-ksp_converged_reason - view the convergence state at the end of the solve
-ksp_use_explicittranspose - transpose the system explicitly in KSPSolveTranspose
-ksp_error_if_not_converged - stop the program as soon as an error is detected in a
KSPSolve()
,KSP_DIVERGED_ITS
is not treated as an error on inner solves-ksp_converged_rate - view the convergence rate at the end of the solve
Notes#
To see all options, run your program with the -help option or consult KSP: Linear System Solvers
See Also#
KSP: Linear System Solvers, KSP
, KSPSetOptionsPrefix()
, KSPResetFromOptions()
, KSPSetUseFischerGuess()
Level#
beginner
Location#
Examples#
src/dm/impls/stag/tutorials/ex1.c
src/dm/impls/stag/tutorials/ex2.c
src/dm/impls/stag/tutorials/ex3.c
src/dm/impls/stag/tutorials/ex4.c
src/dm/impls/stag/tutorials/ex8.c
src/dm/impls/swarm/tutorials/ex1.c
src/dm/impls/swarm/tutorials/ex1f90.F90
src/ksp/ksp/tutorials/bench_kspsolve.c
src/ksp/ksp/tutorials/ex1.c
src/ksp/ksp/tutorials/ex10.c
src/ksp/ksp/tutorials/ex100.c
Implementations#
KSPSetFromOptions_BCGS in src/ksp/ksp/impls/bcgs/bcgs.c
KSPSetFromOptions_BCGSL in src/ksp/ksp/impls/bcgsl/bcgsl.c
KSPSetFromOptions_CG in src/ksp/ksp/impls/cg/cg.c
KSPSetFromOptions_PIPELCG in src/ksp/ksp/impls/cg/pipelcg/pipelcg.c
KSPSetFromOptions_PIPEPRCG in src/ksp/ksp/impls/cg/pipeprcg/pipeprcg.c
KSPSetFromOptions_Chebyshev in src/ksp/ksp/impls/cheby/cheby.c
KSPSetFromOptions_FCG in src/ksp/ksp/impls/fcg/fcg.c
KSPSetFromOptions_PIPEFCG in src/ksp/ksp/impls/fcg/pipefcg/pipefcg.c
KSPSetFromOptions_FETIDP in src/ksp/ksp/impls/fetidp/fetidp.c
KSPSetFromOptions_GCR in src/ksp/ksp/impls/gcr/gcr.c
KSPSetFromOptions_PIPEGCR in src/ksp/ksp/impls/gcr/pipegcr/pipegcr.c
KSPSetFromOptions_AGMRES in src/ksp/ksp/impls/gmres/agmres/agmres.c
KSPSetFromOptions_DGMRES in src/ksp/ksp/impls/gmres/dgmres/dgmres.c
KSPSetFromOptions_FGMRES in src/ksp/ksp/impls/gmres/fgmres/fgmres.c
KSPSetFromOptions_GMRES in src/ksp/ksp/impls/gmres/gmres.c
KSPSetFromOptions_LGMRES in src/ksp/ksp/impls/gmres/lgmres/lgmres.c
KSPSetFromOptions_PGMRES in src/ksp/ksp/impls/gmres/pgmres/pgmres.c
KSPSetFromOptions_PIPEFGMRES in src/ksp/ksp/impls/gmres/pipefgmres/pipefgmres.c
KSPSetFromOptions_HPDDM in src/ksp/ksp/impls/hpddm/hpddm.cxx
KSPSetFromOptions_LCD in src/ksp/ksp/impls/lcd/lcd.c
KSPSetFromOptions_LSQR in src/ksp/ksp/impls/lsqr/lsqr.c
KSPSetFromOptions_MINRES in src/ksp/ksp/impls/minres/minres.c
KSPSetFromOptions_QCG in src/ksp/ksp/impls/qcg/qcg.c
KSPSetFromOptions_Richardson in src/ksp/ksp/impls/rich/rich.c
KSPSetFromOptions_TSIRM in src/ksp/ksp/impls/tsirm/tsirm.c
Index of all KSP routines
Table of Contents for all manual pages
Index of all manual pages