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# KSPFCGSetMmax
set the maximum number of previous directions `KSPFCG` will store for orthogonalization 
## Synopsis
```
#include "petscksp.h"  
PetscErrorCode KSPFCGSetMmax(KSP ksp, PetscInt mmax)
```
Logically Collective


## Input Parameters

- ***ksp -*** the Krylov space context
- ***mmax -*** the maximum number of previous directions to orthogonalize against



## Options Database Key

- ***-ksp_fcg_mmax <N>  -*** maximum number of search directions





## Note
mmax + 1 directions are stored (mmax previous ones along with a current one)
and whether all are used in each iteration also depends on the truncation strategy
(see KSPFCGSetTruncationType())


## See Also
 [](ch_ksp), `KSPFCG`, `KSPFCGGetTruncationType()`, `KSPFCGGetNprealloc()`, `KSPFCGetMmax()`

## Level
intermediate

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