# KSPPIPEGCRSetTruncationType
specify how many of its stored previous directions `KSPPIPEGCR` uses during orthogonalization 
## Synopsis
```
#include "petscksp.h"  
PetscErrorCode KSPPIPEGCRSetTruncationType(KSP ksp, KSPFCDTruncationType truncstrat)
```
Logically Collective


## Input Parameters

- ***ksp -*** the Krylov space context
- ***truncstrat -*** the choice of strategy


```none
  KSP_FCD_TRUNC_TYPE_STANDARD uses all (up to mmax) stored directions
  KSP_FCD_TRUNC_TYPE_NOTAY uses the last max(1,mod(i,mmax)) directions at iteration i=0,1,..
```



## Options Database Key

- ***-ksp_pipegcr_truncation_type <standard,notay> -*** which stored basis vectors to orthogonalize against





## See Also
 [](chapter_ksp), `KSPPIPEGCR`, `KSPPIPEGCRSetTruncationType`, `KSPPIPEGCRTruncationType`, `KSPFCDTruncationType`

## Level
intermediate

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


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