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# KSPPIPEGCRSetNprealloc
set the number of directions to preallocate with `KSPPIPEGCR` 
## Synopsis
```
#include "petscksp.h"  
PetscErrorCode KSPPIPEGCRSetNprealloc(KSP ksp, PetscInt nprealloc)
```
Logically Collective


## Input Parameters

- ***ksp -*** the Krylov space context
- ***nprealloc -*** the number of vectors to preallocate





## Options Database Key

- ***-ksp_pipegcr_nprealloc <N> -*** number of vectors to preallocate



## See Also
 [](ch_ksp), `KSPPIPEGCR`, `KSPPIPEGCRGetTruncationType()`, `KSPPIPEGCRGetNprealloc()`

## Level
advanced

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ksp/ksp/impls/gcr/pipegcr/pipegcr.c.html#KSPPIPEGCRSetNprealloc">src/ksp/ksp/impls/gcr/pipegcr/pipegcr.c</A>


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


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