# KSPQCGSetTrustRegionRadius
Sets the radius of the trust region for `KSPQCG` 
## Synopsis
```
#include "petscksp.h" 
PetscErrorCode KSPQCGSetTrustRegionRadius(KSP ksp, PetscReal delta)
```
Logically Collective


## Input Parameters

- ***ksp   -*** the iterative context
- ***delta -*** the trust region radius (Infinity is the default)



## Options Database Key

- ***-ksp_qcg_trustregionradius <delta> -*** trust region radius





## Level
advanced

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ksp/ksp/impls/qcg/qcg.c.html#KSPQCGSetTrustRegionRadius">src/ksp/ksp/impls/qcg/qcg.c</A>

## Implementations

<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ksp/ksp/impls/qcg/qcg.c.html#KSPQCGSetTrustRegionRadius_QCG">KSPQCGSetTrustRegionRadius_QCG in src/ksp/ksp/impls/qcg/qcg.c</A><BR>


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[Edit on GitLab](https://gitlab.com/petsc/petsc/-/edit/release/src/ksp/ksp/impls/qcg/qcg.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)  
