Actual source code: snesmfj.c
petsc-3.8.4 2018-03-24
2: #include <petsc/private/snesimpl.h>
3: #include <petscdm.h>
4: #include <../src/mat/impls/mffd/mffdimpl.h>
5: #include <petsc/private/matimpl.h>
7: /*@C
8: MatMFFDComputeJacobian - Tells the matrix-free Jacobian object the new location at which
9: Jacobian matrix vector products will be computed at, i.e. J(x) * a. The x is obtained
10: from the SNES object (using SNESGetSolution()).
12: Logically Collective on SNES
14: Input Parameters:
15: + snes - the nonlinear solver context
16: . x - the point at which the Jacobian vector products will be performed
17: . jac - the matrix-free Jacobian object
18: . B - either the same as jac or another matrix type (ignored)
19: . flag - not relevent for matrix-free form
20: - dummy - the user context (ignored)
22: Level: developer
24: Warning:
25: If MatMFFDSetBase() is ever called on jac then this routine will NO longer get
26: the x from the SNES object and MatMFFDSetBase() must from that point on be used to
27: change the base vector x.
29: Notes:
30: This can be passed into SNESSetJacobian() as the Jacobian evaluation function argument
31: when using a completely matrix-free solver,
32: that is the B matrix is also the same matrix operator. This is used when you select
33: -snes_mf but rarely used directly by users. (All this routine does is call MatAssemblyBegin/End() on
34: the Mat jac.)
36: .seealso: MatMFFDGetH(), MatCreateSNESMF(), MatCreateMFFD(), MATMFFD,
37: MatMFFDSetHHistory(), MatMFFDSetFunctionError(), MatCreateMFFD(), SNESSetJacobian()
39: @*/
40: PetscErrorCode MatMFFDComputeJacobian(SNES snes,Vec x,Mat jac,Mat B,void *dummy)
41: {
45: MatAssemblyBegin(jac,MAT_FINAL_ASSEMBLY);
46: MatAssemblyEnd(jac,MAT_FINAL_ASSEMBLY);
47: return(0);
48: }
50: PETSC_EXTERN PetscErrorCode MatAssemblyEnd_MFFD(Mat,MatAssemblyType);
51: PETSC_EXTERN PetscErrorCode MatMFFDSetBase_MFFD(Mat,Vec,Vec);
53: /*
54: MatAssemblyEnd_SNESMF - Calls MatAssemblyEnd_MFFD() and then sets the
55: base from the SNES context
57: */
58: static PetscErrorCode MatAssemblyEnd_SNESMF(Mat J,MatAssemblyType mt)
59: {
61: MatMFFD j = (MatMFFD)J->data;
62: SNES snes = (SNES)j->ctx;
63: Vec u,f;
66: MatAssemblyEnd_MFFD(J,mt);
68: SNESGetSolution(snes,&u);
69: if (j->func == (PetscErrorCode (*)(void*,Vec,Vec))SNESComputeFunction) {
70: SNESGetFunction(snes,&f,NULL,NULL);
71: MatMFFDSetBase_MFFD(J,u,f);
72: } else {
73: /* f value known by SNES is not correct for other differencing function */
74: MatMFFDSetBase_MFFD(J,u,NULL);
75: }
76: return(0);
77: }
79: /*
80: MatAssemblyEnd_SNESMF_UseBase - Calls MatAssemblyEnd_MFFD() and then sets the
81: base from the SNES context. This version will cause the base to be used for differencing
82: even if the func is not SNESComputeFunction. See: MatSNESMFUseBase()
85: */
86: static PetscErrorCode MatAssemblyEnd_SNESMF_UseBase(Mat J,MatAssemblyType mt)
87: {
89: MatMFFD j = (MatMFFD)J->data;
90: SNES snes = (SNES)j->ctx;
91: Vec u,f;
94: MatAssemblyEnd_MFFD(J,mt);
96: SNESGetSolution(snes,&u);
97: SNESGetFunction(snes,&f,NULL,NULL);
98: MatMFFDSetBase_MFFD(J,u,f);
99: return(0);
100: }
102: /*
103: This routine resets the MatAssemblyEnd() for the MatMFFD created from MatCreateSNESMF() so that it NO longer
104: uses the solution in the SNES object to update the base. See the warning in MatCreateSNESMF().
105: */
106: static PetscErrorCode MatMFFDSetBase_SNESMF(Mat J,Vec U,Vec F)
107: {
111: MatMFFDSetBase_MFFD(J,U,F);
112: J->ops->assemblyend = MatAssemblyEnd_MFFD;
113: return(0);
114: }
116: static PetscErrorCode MatSNESMFSetReuseBase_SNESMF(Mat J,PetscBool use)
117: {
119: if (use) {
120: J->ops->assemblyend = MatAssemblyEnd_SNESMF_UseBase;
121: } else {
122: J->ops->assemblyend = MatAssemblyEnd_SNESMF;
123: }
124: return(0);
125: }
127: /*@
128: MatSNESMFSetReuseBase - Causes the base vector to be used for differencing even if the function provided to SNESSetFunction() is not the
129: same as that provided to MatMFFDSetFunction().
131: Logically Collective on Mat
133: Input Parameters:
134: + J - the MatMFFD matrix
135: - use - if true always reuse the base vector instead of recomputing f(u) even if the function in the MatSNESMF is
136: not SNESComputeFunction()
138: Notes: Care must be taken when using this routine to insure that the function provided to MatMFFDSetFunction(), call it F_MF() is compatible with
139: with that provided to SNESSetFunction(), call it F_SNES(). That is, (F_MF(u + h*d) - F_SNES(u))/h has to approximate the derivative
141: Developer Notes: This was provided for the MOOSE team who desired to have a SNESSetFunction() function that could change configurations due
142: to contacts while the function provided to MatMFFDSetFunction() cannot. Except for the possibility of changing the configuration
143: both functions compute the same mathematical function so the differencing makes sense.
145: Level: advanced
147: .seealso: MatCreateSNESMF(), MatSNESMFGetReuseBase()
148: @*/
149: PetscErrorCode MatSNESMFSetReuseBase(Mat J,PetscBool use)
150: {
155: PetscTryMethod(J,"MatSNESMFSetReuseBase_C",(Mat,PetscBool),(J,use));
156: return(0);
157: }
159: static PetscErrorCode MatSNESMFGetReuseBase_SNESMF(Mat J,PetscBool *use)
160: {
162: if (J->ops->assemblyend == MatAssemblyEnd_SNESMF_UseBase) *use = PETSC_TRUE;
163: else *use = PETSC_FALSE;
164: return(0);
165: }
167: /*@
168: MatSNESMFGetReuseBase - Determines if the base vector is to be used for differencing even if the function provided to SNESSetFunction() is not the
169: same as that provided to MatMFFDSetFunction().
171: Logically Collective on Mat
173: Input Parameter:
174: . J - the MatMFFD matrix
176: Output Parameter:
177: . use - if true always reuse the base vector instead of recomputing f(u) even if the function in the MatSNESMF is
178: not SNESComputeFunction()
180: Notes: Care must be taken when using this routine to insure that the function provided to MatMFFDSetFunction(), call it F_MF() is compatible with
181: with that provided to SNESSetFunction(), call it F_SNES(). That is, (F_MF(u + h*d) - F_SNES(u))/h has to approximate the derivative
183: Developer Notes: This was provided for the MOOSE team who desired to have a SNESSetFunction() function that could change configurations due
184: to contacts while the function provided to MatMFFDSetFunction() cannot. Except for the possibility of changing the configuration
185: both functions compute the same mathematical function so the differencing makes sense.
187: Level: advanced
189: .seealso: MatCreateSNESMF(), MatSNESMFSetReuseBase()
190: @*/
191: PetscErrorCode MatSNESMFGetReuseBase(Mat J,PetscBool *use)
192: {
197: PetscUseMethod(J,"MatSNESMFGetReuseBase_C",(Mat,PetscBool*),(J,use));
198: return(0);
199: }
201: /*@
202: MatCreateSNESMF - Creates a matrix-free matrix context for use with
203: a SNES solver. This matrix can be used as the Jacobian argument for
204: the routine SNESSetJacobian(). See MatCreateMFFD() for details on how
205: the finite difference computation is done.
207: Collective on SNES and Vec
209: Input Parameters:
210: . snes - the SNES context
212: Output Parameter:
213: . J - the matrix-free matrix
215: Level: advanced
218: Notes:
219: You can call SNESSetJacobian() with MatMFFDComputeJacobian() if you are using matrix and not a different
220: preconditioner matrix
222: If you wish to provide a different function to do differencing on to compute the matrix-free operator than
223: that provided to SNESSetFunction() then call MatMFFDSetFunction() with your function after this call.
225: The difference between this routine and MatCreateMFFD() is that this matrix
226: automatically gets the current base vector from the SNES object and not from an
227: explicit call to MatMFFDSetBase().
229: Warning:
230: If MatMFFDSetBase() is ever called on jac then this routine will NO longer get
231: the x from the SNES object and MatMFFDSetBase() must from that point on be used to
232: change the base vector x.
234: Warning:
235: Using a different function for the differencing will not work if you are using non-linear left preconditioning.
238: .seealso: MatDestroy(), MatMFFDSetFunction(), MatMFFDSetFunctionError(), MatMFFDDSSetUmin()
239: MatMFFDSetHHistory(), MatMFFDResetHHistory(), MatCreateMFFD(),
240: MatMFFDGetH(), MatMFFDRegister(), MatMFFDComputeJacobian(), MatSNESMFSetReuseBase(), MatSNESMFGetReuseBase()
242: @*/
243: PetscErrorCode MatCreateSNESMF(SNES snes,Mat *J)
244: {
246: PetscInt n,N;
247: MatMFFD mf;
250: if (snes->vec_func) {
251: VecGetLocalSize(snes->vec_func,&n);
252: VecGetSize(snes->vec_func,&N);
253: } else if (snes->dm) {
254: Vec tmp;
255: DMGetGlobalVector(snes->dm,&tmp);
256: VecGetLocalSize(tmp,&n);
257: VecGetSize(tmp,&N);
258: DMRestoreGlobalVector(snes->dm,&tmp);
259: } else SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_WRONGSTATE,"Must call SNESSetFunction() or SNESSetDM() first");
260: MatCreateMFFD(PetscObjectComm((PetscObject)snes),n,n,N,N,J);
262: mf = (MatMFFD)(*J)->data;
263: mf->ctx = snes;
265: if (snes->npc && snes->npcside== PC_LEFT) {
266: MatMFFDSetFunction(*J,(PetscErrorCode (*)(void*,Vec,Vec))SNESComputeFunctionDefaultNPC,snes);
267: } else {
268: MatMFFDSetFunction(*J,(PetscErrorCode (*)(void*,Vec,Vec))SNESComputeFunction,snes);
269: }
271: (*J)->ops->assemblyend = MatAssemblyEnd_SNESMF;
273: PetscObjectComposeFunction((PetscObject)*J,"MatMFFDSetBase_C",MatMFFDSetBase_SNESMF);
274: PetscObjectComposeFunction((PetscObject)*J,"MatSNESMFSetReuseBase_C",MatSNESMFSetReuseBase_SNESMF);
275: PetscObjectComposeFunction((PetscObject)*J,"MatSNESMFGetReuseBase_C",MatSNESMFGetReuseBase_SNESMF);
276: return(0);
277: }