petsc-3.12.4 2020-02-04
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# TaoLineSearchSetObjectiveRoutine

Sets the function evaluation routine for the line search

### Synopsis

    #include "petsctaolinesearch.h"
    PetscErrorCode TaoLineSearchSetObjectiveRoutine(TaoLineSearch ls, PetscErrorCode(*func)(TaoLineSearch ls, Vec x, PetscReal*, void*), void *ctx)

Logically Collective on TaoLineSearch

### Input Parameter

| ls | - the TaoLineSearch context
| func | - the objective function evaluation routine
| ctx | - the (optional) user-defined context for private data

### Calling sequence of func

         func (TaoLinesearch ls, Vec x, PetscReal *f, void *ctx);

| x | - input vector
| f | - function value
| ctx (optional) user | - defined context

### Note

Use this routine only if you want the line search objective evaluation routine to be different from the Tao's objective evaluation routine. If you use this routine you must also set the line search gradient and/or function/gradient routine.

### Note

Some algorithms (lcl, gpcg) set their own objective routine for the line search, application programmers should be wary of overriding the default objective routine.

### See Also

TaoLineSearchCreate(), TaoLineSearchSetGradientRoutine(), TaoLineSearchSetObjectiveAndGradientRoutine(), TaoLineSearchUseTaoRoutines()

### Level

beginner

### Location

src/tao/linesearch/interface/taolinesearch.c
Index of all TaoLineSearch routines
Table of Contents for all manual pages
Index of all manual pages