# KSPGetConvergenceTest
Gets the function to be used to determine convergence. 
## Synopsis
```
#include "petscksp.h" 
#include "petscmat.h" 
PetscErrorCode KSPGetConvergenceTest(KSP ksp, PetscErrorCode (**converge)(KSP, PetscInt, PetscReal, KSPConvergedReason *, void *), void **cctx, PetscErrorCode (**destroy)(void *))
```
Logically Collective on ksp


## Input Parameter

- ***ksp -*** iterative context obtained from `KSPCreate()`



## Output Parameters

- ***converge -*** pointer to convergence test function
- ***cctx    -*** context for private data for the convergence routine (may be null)
- ***destroy -*** a routine for destroying the context (may be null)



## Calling sequence of converge
```none
converge (`KSP` ksp, `PetscInt` it, `PetscReal` rnorm, `KSPConvergedReason` *reason,void *mctx)
```


- ***ksp -*** iterative context obtained from `KSPCreate()`
- ***it -*** iteration number
- ***rnorm -*** (estimated) 2-norm of (preconditioned) residual
- ***reason -*** the reason why it has converged or diverged
- ***cctx  -*** optional convergence context, as set by `KSPSetConvergenceTest()`





## See Also
 [](chapter_ksp), `KSP`, `KSPConvergedDefault()`, `KSPGetConvergenceContext()`, `KSPSetTolerances()`, `KSP`, `KSPSetConvergenceTest()`, `KSPGetAndClearConvergenceTest()`

## Level
advanced

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ksp/ksp/interface/itfunc.c.html#KSPGetConvergenceTest">src/ksp/ksp/interface/itfunc.c</A>


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[Edit on GitLab](https://gitlab.com/petsc/petsc/-/edit/release/src/ksp/ksp/interface/itfunc.c)


[Index of all KSP routines](index.md)  
[Table of Contents for all manual pages](/docs/manualpages/index.md)  
[Index of all manual pages](/docs/manualpages/singleindex.md)  
