# KSPMonitorDynamicTolerance
Recompute the inner tolerance in every outer iteration in an adaptive way. 
## Synopsis
```
#include "petscksp.h" 
PetscErrorCode KSPMonitorDynamicTolerance(KSP ksp, PetscInt its, PetscReal fnorm, void *dummy)
```
Collective


## Input Parameters

- ***ksp   -*** iterative context
- ***n     -*** iteration number (not used)
- ***fnorm -*** the current residual norm
- ***dummy -*** some context as a C struct. fields:
coef: a scaling coefficient. default 1.0. can be passed through
-sub_ksp_dynamic_tolerance_param
bnrm: norm of the right-hand side. store it to avoid repeated calculation



## Notes
This may be useful for a flexibly preconditioner Krylov method to
control the accuracy of the inner solves needed to guarantee the
convergence of the outer iterations.

This is not called directly by users, rather one calls `KSPMonitorSet()`, with this function as an argument, to cause the monitor
to be used during the KSP solve.




## See Also
 `KSPMonitorDynamicToleranceDestroy()`

## Level
advanced

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


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


[Index of all KSP routines](index.md)  
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