SNESSetFromOptions#
Sets various SNES
and KSP
parameters from user options.
Synopsis#
#include "petscsnes.h"
PetscErrorCode SNESSetFromOptions(SNES snes)
Collective
Input Parameter#
snes - the
SNES
context
Options Database Keys#
-snes_type
- newtonls, newtontr, ngmres, ncg, nrichardson, qn, vi, fas,SNESType
for complete list-snes_rtol
- relative decrease in tolerance norm from initial-snes_atol
- absolute tolerance of residual norm-snes_stol
- convergence tolerance in terms of the norm of the change in the solution between steps-snes_divergence_tolerance
- if the residual goes above divtol*rnorm0, exit with divergence-snes_max_it <max_it> - maximum number of iterations
-snes_max_funcs <max_funcs> - maximum number of function evaluations
-snes_force_iteration
- forceSNESSolve()
to take at least one iteration-snes_max_fail <max_fail> - maximum number of line search failures allowed before stopping, default is none
-snes_max_linear_solve_fail - number of linear solver failures before SNESSolve() stops
-snes_lag_preconditioner
- how often preconditioner is rebuilt (use -1 to never rebuild)-snes_lag_preconditioner_persists <true,false> - retains the -snes_lag_preconditioner information across multiple SNESSolve()
-snes_lag_jacobian
- how often Jacobian is rebuilt (use -1 to never rebuild)-snes_lag_jacobian_persists <true,false> - retains the -snes_lag_jacobian information across multiple SNESSolve()
-snes_convergence_test <default,skip,correct_pressure> - convergence test in nonlinear solver. default
SNESConvergedDefault()
. skipSNESConvergedSkip()
means continue iterating until max_it or some other criterion is reached, saving expense of convergence test. correct_pressureSNESConvergedCorrectPressure()
has special handling of a pressure null space.-snes_monitor [ascii][:filename][:viewer format] - prints residual norm at each iteration. if no filename given prints to stdout
-snes_monitor_solution [ascii binary draw][:filename][:viewer format] - plots solution at each iteration
-snes_monitor_residual [ascii binary draw][:filename][:viewer format] - plots residual (not its norm) at each iteration
-snes_monitor_solution_update [ascii binary draw][:filename][:viewer format] - plots update to solution at each iteration
-snes_monitor_lg_residualnorm - plots residual norm at each iteration
-snes_monitor_lg_range - plots residual norm at each iteration
-snes_monitor_pause_final - Pauses all monitor drawing after the solver ends
-snes_fd - use finite differences to compute Jacobian; very slow, only for testing
-snes_fd_color - use finite differences with coloring to compute Jacobian
-snes_mf_ksp_monitor - if using matrix-free multiply then print h at each
KSP
iteration-snes_converged_reason - print the reason for convergence/divergence after each solve
-npc_snes_type
- theSNES
type to use as a nonlinear preconditioner-snes_test_jacobian
- compare the user provided Jacobian with one computed via finite differences to check for errors. If a threshold is given, display only those entries whose difference is greater than the threshold.-snes_test_jacobian_view - display the user provided Jacobian, the finite difference Jacobian and the difference between them to help users detect the location of errors in the user provided Jacobian.
Options Database Keys for Eisenstat-Walker method#
-snes_ksp_ew - use Eisenstat-Walker method for determining linear system convergence
-snes_ksp_ew_version ver - version of Eisenstat-Walker method
-snes_ksp_ew_rtol0
- Sets rtol0-snes_ksp_ew_rtolmax
- Sets rtolmax-snes_ksp_ew_gamma
- Sets gamma-snes_ksp_ew_alpha
- Sets alpha-snes_ksp_ew_alpha2
- Sets alpha2-snes_ksp_ew_threshold
- Sets threshold
Notes#
To see all options, run your program with the -help option or consult the users manual
SNES
supports three approaches for computing (approximate) Jacobians: user provided via SNESSetJacobian()
, matrix-free using MatCreateSNESMF()
,
and computing explicitly with
finite differences and coloring using MatFDColoring
. It is also possible to use automatic differentiation and the MatFDColoring
object.
See Also#
SNES: Nonlinear Solvers, SNESType
, SNESSetOptionsPrefix()
, SNESResetFromOptions()
, SNES
, SNESCreate()
, MatCreateSNESMF()
, MatFDColoring
Level#
beginner
Location#
Examples#
src/snes/tutorials/ex48.c
src/tao/tutorials/ex1.c
src/ts/tutorials/ex30.c
src/snes/tutorials/ex35.c
src/tao/tutorials/ex2.c
src/snes/tutorials/ex77.c
src/snes/tutorials/ex55.c
src/snes/tutorials/ex69.c
src/snes/tutorials/ex26.c
src/ts/tutorials/ex27.c
Implementations#
SNESSetFromOptions_NEWTONAL() in src/snes/impls/al/al.c
SNESSetFromOptions_Composite() in src/snes/impls/composite/snescomposite.c
SNESSetFromOptions_FAS() in src/snes/impls/fas/fas.c
SNESSetFromOptions_NGS() in src/snes/impls/gs/snesgs.c
SNESSetFromOptions_NEWTONLS() in src/snes/impls/ls/ls.c
SNESSetFromOptions_MS() in src/snes/impls/ms/ms.c
SNESSetFromOptions_Multiblock() in src/snes/impls/multiblock/multiblock.c
SNESSetFromOptions_NASM() in src/snes/impls/nasm/nasm.c
SNESSetFromOptions_NCG() in src/snes/impls/ncg/snesncg.c
SNESSetFromOptions_Anderson() in src/snes/impls/ngmres/anderson.c
SNESSetFromOptions_NGMRES() in src/snes/impls/ngmres/snesngmres.c
SNESSetFromOptions_NEWTONTRDC() in src/snes/impls/ntrdc/ntrdc.c
SNESSetFromOptions_Patch() in src/snes/impls/patch/snespatch.c
SNESSetFromOptions_QN() in src/snes/impls/qn/qn.c
SNESSetFromOptions_NRichardson() in src/snes/impls/richardson/snesrichardson.c
SNESSetFromOptions_Shell() in src/snes/impls/shell/snesshell.c
SNESSetFromOptions_NEWTONTR() in src/snes/impls/tr/tr.c
SNESSetFromOptions_VINEWTONSSLS() in src/snes/impls/vi/ss/viss.c
SNESSetFromOptions_VI() in src/snes/impls/vi/vi.c
Index of all SNES routines
Table of Contents for all manual pages
Index of all manual pages