# KSPFCGSetTruncationType
specify how many of its stored previous directions `KSPFCG` uses during orthoganalization 
## Synopsis
```
#include "petscksp.h"  
PetscErrorCode KSPFCGSetTruncationType(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)) stored directions at iteration i=0,1,..
```



## Options Database Key

- ***-ksp_fcg_truncation_type <standard, notay> -*** specify how many of its stored previous directions `KSPFCG` uses during orthoganalization





## See Also
 [](chapter_ksp), `KSPFCDTruncationType`, `KSPFCGGetTruncationType`, `KSPFCGSetNprealloc()`, `KSPFCGSetMmax()`, `KSPFCGGetMmax()`

## Level
intermediate

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


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


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