KSPFCGSetTruncationType — PETSc 3.21.4 documentation

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# 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

      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

KSP: Linear System Solvers, `KSPFCDTruncationType`, `KSPFCGGetTruncationType()`, `KSPFCGSetNprealloc()`, `KSPFCGSetMmax()`, `KSPFCGGetMmax()`, `KSP_FCD_TRUNC_TYPE_STANDARD`, `KSP_FCD_TRUNC_TYPE_NOTAY`

## Level

intermediate

## Location

src/ksp/ksp/impls/fcg/fcg.c

Index of all KSP routines
Table of Contents for all manual pages
Index of all manual pages