Actual source code: snesmfj.c
1: #define PETSCSNES_DLL
3: #include include/private/snesimpl.h
4: #include include/private/matimpl.h
5: #include src/mat/impls/mffd/mffdimpl.h
9: /*@
10: MatMFFDComputeJacobian - Tells the matrix-free Jacobian object the new location at which
11: Jacobian matrix vector products will be computed at, i.e. J(x) * a. The x is obtained
12: from the SNES object (using SNESGetSolution()).
14: Collective on SNES
16: Input Parameters:
17: + snes - the nonlinear solver context
18: . x - the point at which the Jacobian vector products will be performed
19: . jac - the matrix-free Jacobian object
20: . B - either the same as jac or another matrix type (ignored)
21: . flag - not relevent for matrix-free form
22: - dummy - the user context (ignored)
24: Level: developer
26: Warning:
27: If MatMFFDSetBase() is ever called on jac then this routine will NO longer get
28: the x from the SNES object and MatMFFDSetBase() must from that point on be used to
29: change the base vector x.
31: Notes:
32: This can be passed into SNESSetJacobian() when using a completely matrix-free solver,
33: that is the B matrix is also the same matrix operator. This is used when you select
34: -snes_mf but rarely used directly by users.
36: .seealso: MatMFFDGetH(), MatCreateSNESMF(), MatCreateMFFD(), MATMFFD,
37: MatMFFDSetHHistory(),
38: MatMFFDKSPMonitor(), MatMFFDSetFunctionError(), MatMFFDCreate(), SNESSetJacobian()
40: @*/
41: PetscErrorCode MatMFFDComputeJacobian(SNES snes,Vec x,Mat *jac,Mat *B,MatStructure *flag,void *dummy)
42: {
45: MatAssemblyBegin(*jac,MAT_FINAL_ASSEMBLY);
46: MatAssemblyEnd(*jac,MAT_FINAL_ASSEMBLY);
47: return(0);
48: }
50: PetscErrorCode MatAssemblyEnd_MFFD(Mat,MatAssemblyType);
53: /*
54: MatAssemblyEnd_SNESMF - Calls MatAssemblyEnd_MFFD() and then sets the
55: base from the SNES context
57: */
58: PetscErrorCode MatAssemblyEnd_SNESMF(Mat J,MatAssemblyType mt)
59: {
61: MatMFFD j = (MatMFFD)J->data;
62: SNES snes = (SNES)j->funcctx;
63: Vec u,f;
66: MatAssemblyEnd_MFFD(J,mt);
68: SNESGetSolution(snes,&u);
69: SNESGetFunction(snes,&f,PETSC_NULL,PETSC_NULL);
70: MatMFFDSetBase(J,u,f);
71: return(0);
72: }
76: /*
77: This routine resets the MatAssemblyEnd() for the MatMFFD created from MatCreateSNESMF() so that it NO longer
78: uses the solution in the SNES object to update the base. See the warning in MatCreateSNESMF().
79: */
82: PetscErrorCode MatMFFDSetBase_SNESMF(Mat J,Vec U,Vec F)
83: {
87: MatMFFDSetBase_MFFD(J,U,F);
88: J->ops->assemblyend = MatAssemblyEnd_MFFD;
89: return(0);
90: }
95: /*@
96: MatCreateSNESMF - Creates a matrix-free matrix context for use with
97: a SNES solver. This matrix can be used as the Jacobian argument for
98: the routine SNESSetJacobian(). See MatCreateMFFD() for details on how
99: the finite difference computation is done.
101: Collective on SNES and Vec
103: Input Parameters:
104: . snes - the SNES context
106: Output Parameter:
107: . J - the matrix-free matrix
109: Level: advanced
111: Warning:
112: If MatMFFDSetBase() is ever called on jac then this routine will NO longer get
113: the x from the SNES object and MatMFFDSetBase() must from that point on be used to
114: change the base vector x.
116: Notes: The difference between this routine and MatCreateMFFD() is that this matrix
117: automatically gets the current base vector from the SNES object and not from an
118: explicit call to MatMFFDSetBase().
120: .seealso: MatDestroy(), MatMFFDSetFunctionError(), MatMFFDDefaultSetUmin()
121: MatMFFDSetHHistory(), MatMFFDResetHHistory(), MatCreateMFFD(),
122: MatMFFDGetH(),MatMFFDKSPMonitor(), MatMFFDRegisterDynamic), MatMFFDComputeJacobian()
123:
124: @*/
125: PetscErrorCode MatCreateSNESMF(SNES snes,Mat *J)
126: {
128: PetscInt n,N;
131: if (!snes->vec_func) SETERRQ(PETSC_ERR_ARG_WRONGSTATE,"SNESSetFunction() must be called first");
132:
133: VecGetLocalSize(snes->vec_func,&n);
134: VecGetSize(snes->vec_func,&N);
135: MatCreateMFFD(((PetscObject)snes)->comm,n,n,N,N,J);
136: MatMFFDSetFunction(*J,(PetscErrorCode (*)(void*,Vec,Vec))SNESComputeFunction,snes);
137: (*J)->ops->assemblyend = MatAssemblyEnd_SNESMF;
138: PetscObjectComposeFunctionDynamic((PetscObject)*J,"MatMFFDSetBase_C","MatMFFDSetBase_SNESMF",MatMFFDSetBase_SNESMF);
139: return(0);
140: }