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# KSPGuessCreate

Creates a `KSPGuess` context.

## Synopsis

    #include "petscksp.h"
    PetscErrorCode KSPGuessCreate(MPI_Comm comm, KSPGuess *guess)

Collective

## Input Parameter

- comm - MPI communicator

## Output Parameter

- guess - location to put the `KSPGuess` context

## Options Database Keys

- -ksp_guess_type type - Turns on generation of initial guesses and sets the method; see `KSPGuessType`

- -ksp_guess_view viewer - view the `KSPGuess` object

- -ksp_guess_fischer_model a,b - set details for the Fischer models

- -ksp_guess_fischer_monitor - monitor the fischer models

- -ksp_guess_fischer_tol tol - set the tolerance for the Fischer models

- -ksp_guess_pod_size size - Number of snapshots

- -ksp_guess_pod_monitor - monitor the pod initial guess processing

- -ksp_guess_pod_tol tol - Tolerance to retain eigenvectors

- -ksp_guess_pod_Ainner (true|false) - Use the operator as inner product (must be SPD)

## Note

These are generally created automatically by using the option `-ksp_guess_type type` and controlled from the options database

There are two families of methods `KSPGUESSFISCHER`, developed by Paul Fischer and `KSPGUESSPOD`

## See Also

KSP: Linear System Solvers, `KSPSolve()`, `KSPGuessDestroy()`, `KSPGuess`, `KSPGuessType`, `KSP`

## Level

developer

## Location

src/ksp/ksp/interface/iguess.c

## Implementations

KSPGuessCreate_Fischer() in src/ksp/ksp/guess/impls/fischer/fischer.c
KSPGuessCreate_POD() in src/ksp/ksp/guess/impls/pod/pod.c

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