# SNESConverged_TR

Monitors the convergence of the trust region method SNESTR for solving systems of nonlinear equations (default).

### Synopsis

    #include "petscsnes.h"
    PetscErrorCode PETSCSNES_DLLEXPORT SNESConverged_TR(SNES snes,PetscInt it,PetscReal xnorm,PetscReal pnorm,PetscReal fnorm,SNESConvergedReason *reason,void *dummy)

Collective on SNES

### Input Parameters

| snes | - the SNES context
| xnorm | - 2-norm of current iterate
| pnorm | - 2-norm of current step
| fnorm | - 2-norm of function
| dummy | - unused context

### Output Parameter

reason -one of

     SNES_CONVERGED_FNORM_ABS       - (fnorm < abstol),

     SNES_CONVERGED_PNORM_RELATIVE  - (pnorm < xtol*xnorm),

     SNES_CONVERGED_FNORM_RELATIVE  - (fnorm < rtol*fnorm0),

     SNES_DIVERGED_FUNCTION_COUNT   - (nfct > maxf),

     SNES_DIVERGED_FNORM_NAN        - (fnorm == NaN),

     SNES_CONVERGED_TR_DELTA        - (delta < xnorm*deltatol),

     SNES_CONVERGED_ITERATING       - (otherwise)

where

| delta | - trust region paramenter
| deltatol | - trust region size tolerance, set with SNESSetTrustRegionTolerance()
| maxf | - maximum number of function evaluations, set with SNESSetTolerances()
| nfct | - number of function evaluations,
| abstol | - absolute function norm tolerance, set with SNESSetTolerances()
| xtol | - relative function norm tolerance, set with SNESSetTolerances()

### Keywords

SNES, nonlinear, default, converged, convergence

### See Also

SNESSetConvergenceTest(), SNESEisenstatWalkerConverged()

Level:intermediate
Location: src/snes/impls/tr/tr.c
Index of all SNES routines
Table of Contents for all manual pages
Index of all manual pages