Actual source code: mffdimpl.h
1: /*
2: This file should be included in NEW routines that compute the
3: differencing parameter for finite difference based matrix-free
4: methods. For example, such routines can compute h for use in
5: Jacobian-vector products of the form
7: F(x+ha) - F(x)
8: F'(u)a ~= ----------------
9: h
10: */
11: #ifndef PETSC_MFFDIMPL_H
12: #define PETSC_MFFDIMPL_H
14: #include <petscmat.h>
15: #include <petsc/private/petscimpl.h>
17: /*
18: Table of functions that manage the computation and understanding
19: of the parameter for finite difference based matrix-free computations
20: */
21: struct _MFOps {
22: PetscErrorCode (*compute)(MatMFFD, Vec, Vec, PetscScalar *, PetscBool *zeroa);
23: PetscErrorCode (*view)(MatMFFD, PetscViewer);
24: PetscErrorCode (*destroy)(MatMFFD);
25: PetscErrorCode (*setfromoptions)(MatMFFD, PetscOptionItems *);
26: };
28: /* context for default matrix-free SNES */
29: struct _p_MatMFFD {
30: PETSCHEADER(struct _MFOps);
31: Vec w; /* work vector */
32: PetscReal error_rel; /* square root of relative error in computing function */
33: PetscScalar currenth; /* last differencing parameter h used */
34: PetscScalar *historyh; /* history of differencing parameter h */
35: PetscInt ncurrenth, maxcurrenth;
36: void *hctx;
37: Mat mat; /* back reference to shell matrix that contains this */
38: PetscInt recomputeperiod; /* how often the h is recomputed; default to 1 */
39: PetscInt count; /* used by recomputeperiod */
40: PetscErrorCode (*checkh)(void *, Vec, Vec, PetscScalar *);
41: void *checkhctx; /* optional context used by MatMFFDSetCheckh() */
43: PetscErrorCode (*func)(void *, Vec, Vec); /* function used for matrix free */
44: void *funcctx; /* the context for the function */
45: Vec current_f; /* location of F(u); used with F(u+h) */
46: PetscBool current_f_allocated;
47: Vec current_u; /* location of u; used with F(u+h) */
49: PetscErrorCode (*funci)(void *, PetscInt, Vec, PetscScalar *); /* Evaluates func_[i]() */
50: PetscErrorCode (*funcisetbase)(void *, Vec); /* Sets base for future evaluations of func_[i]() */
52: void *ctx; /* this is used by MatCreateSNESMF() to store the SNES object */
53: #if defined(PETSC_USE_COMPLEX)
54: PetscBool usecomplex; /* use Lyness complex number trick to compute the matrix-vector product */
55: #endif
56: };
58: PETSC_EXTERN PetscFunctionList MatMFFDList;
59: PETSC_EXTERN PetscBool MatMFFDRegisterAllCalled;
60: PETSC_EXTERN PetscErrorCode MatMFFDRegisterAll(void);
62: #endif // PETSC_MFFDIMPL_H