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


## Input Parameters

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



## Options Database Key

- ***-ksp_pipefcg_nprealloc <N> -*** the number of vectors to preallocate





## See Also
 [](ch_ksp), `KSPPIPEFCG`, `KSPPIPEFCGSetTruncationType()`, `KSPPIPEFCGGetNprealloc()`, `KSPPIPEFCGSetMmax()`, `KSPPIPEFCGGetMmax()`

## Level
advanced

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ksp/ksp/impls/fcg/pipefcg/pipefcg.c.html#KSPPIPEFCGSetNprealloc">src/ksp/ksp/impls/fcg/pipefcg/pipefcg.c</A>


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


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