petsc-3.7.3 2016-07-24
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# KSPSetInitialGuessNonzero

Tells the iterative solver that the initial guess is nonzero; otherwise KSP assumes the initial guess is to be zero (and thus zeros it out before solving).

### Synopsis

    #include "petscksp.h"
    PetscErrorCode  KSPSetInitialGuessNonzero(KSP ksp,PetscBool flg)

Logically Collective on KSP

### Input Parameters

| ksp | - iterative context obtained from KSPCreate()
| flg | - PETSC_TRUE indicates the guess is non-zero, PETSC_FALSE indicates the guess is zero

### Options database keys

-ksp_initial_guess_nonzero : use nonzero initial guess; this takes an optional truth value (0/1/no/yes/true/false) -

### Notes

If this is not called the X vector is zeroed in the call to KSPSolve().

### Keywords

KSP, set, initial guess, nonzero

### See Also

KSPGetInitialGuessNonzero(), KSPSetInitialGuessKnoll(), KSPGetInitialGuessKnoll()

Level:beginner
Location: src/ksp/ksp/interface/itfunc.c
Index of all KSP routines
Table of Contents for all manual pages
Index of all manual pages

### Examples

src/ksp/pc/examples/tutorials/ex1.c.html
src/ksp/pc/examples/tutorials/ex2.c.html
src/ksp/ksp/examples/tutorials/ex1.c.html
src/ksp/ksp/examples/tutorials/ex3.c.html
src/ksp/ksp/examples/tutorials/ex9.c.html
src/ksp/ksp/examples/tutorials/ex10.c.html
src/ksp/ksp/examples/tutorials/ex51.c.html
src/ksp/ksp/examples/tutorials/ex56.c.html
src/ksp/ksp/examples/tutorials/ex58.c.html
src/ksp/ksp/examples/tutorials/ex6f.F.html
src/tao/pde_constrained/examples/tutorials/parabolic.c.html