1 #include <petsc/private/snesimpl.h> /*I "petscsnes.h" I*/
2
3 /*@
4 SNESApplyNPC - Calls `SNESSolve()` on the preconditioner for the `SNES`
5
6 Collective
7
8 Input Parameters:
9 + snes - the `SNES` context
10 . x - input vector
11 - f - optional; the function evaluation on `x`
12
13 Output Parameter:
14 . y - function vector, as set by `SNESSetFunction()`
15
16 Level: developer
17
18 Note:
19 `SNESComputeFunction()` should be called on `x` before `SNESApplyNPC()` is called, as it is
20 with `SNESComuteJacobian()`.
21
22 .seealso: [](ch_snes), `SNES`, `SNESGetNPC()`, `SNESSetNPC()`, `SNESComputeFunction()`
23 @*/
SNESApplyNPC(SNES snes,Vec x,Vec f,Vec y)24 PetscErrorCode SNESApplyNPC(SNES snes, Vec x, Vec f, Vec y)
25 {
26 PetscFunctionBegin;
27 PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
28 PetscValidHeaderSpecific(x, VEC_CLASSID, 2);
29 PetscValidHeaderSpecific(y, VEC_CLASSID, 4);
30 PetscCheckSameComm(snes, 1, x, 2);
31 PetscCheckSameComm(snes, 1, y, 4);
32 PetscCall(VecValidValues_Internal(x, 2, PETSC_TRUE));
33 if (snes->npc) {
34 if (f) PetscCall(SNESSetInitialFunction(snes->npc, f));
35 PetscCall(VecCopy(x, y));
36 PetscCall(PetscLogEventBegin(SNES_NPCSolve, snes->npc, x, y, 0));
37 PetscCall(SNESSolve(snes->npc, snes->vec_rhs, y));
38 PetscCall(PetscLogEventEnd(SNES_NPCSolve, snes->npc, x, y, 0));
39 PetscCall(VecAYPX(y, -1.0, x));
40 }
41 PetscFunctionReturn(PETSC_SUCCESS);
42 }
43
SNESComputeFunctionDefaultNPC(SNES snes,Vec X,Vec F)44 PetscErrorCode SNESComputeFunctionDefaultNPC(SNES snes, Vec X, Vec F)
45 {
46 /* This is to be used as an argument to SNESMF -- NOT as a "function" */
47 SNESConvergedReason reason;
48
49 PetscFunctionBegin;
50 if (snes->npc) {
51 PetscCall(SNESApplyNPC(snes, X, NULL, F));
52 PetscCall(SNESGetConvergedReason(snes->npc, &reason));
53 if (reason < 0 && reason != SNES_DIVERGED_MAX_IT) PetscCall(SNESSetFunctionDomainError(snes));
54 } else {
55 PetscCall(SNESComputeFunction(snes, X, F));
56 }
57 PetscFunctionReturn(PETSC_SUCCESS);
58 }
59
60 /*@
61 SNESGetNPCFunction - Gets the current function value (for the callback function provided by `SNESSetFunction()`,
62 and its norm from a nonlinear preconditioner after `SNESSolve()` has been called on that `SNES`
63
64 Collective
65
66 Input Parameter:
67 . snes - the `SNES` context
68
69 Output Parameters:
70 + F - function vector
71 - fnorm - the norm of `F`
72
73 Level: developer
74
75 .seealso: [](ch_snes), `SNES`, `SNESGetNPC()`, `SNESSetNPC()`, `SNESComputeFunction()`, `SNESApplyNPC()`, `SNESSolve()`
76 @*/
SNESGetNPCFunction(SNES snes,Vec F,PetscReal * fnorm)77 PetscErrorCode SNESGetNPCFunction(SNES snes, Vec F, PetscReal *fnorm)
78 {
79 PCSide npcside;
80 SNESFunctionType functype;
81 SNESNormSchedule normschedule;
82 Vec FPC, XPC;
83
84 PetscFunctionBegin;
85 PetscValidHeaderSpecific(snes, SNES_CLASSID, 1);
86 if (fnorm) PetscAssertPointer(fnorm, 3);
87 PetscCheck(snes->npc, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONGSTATE, "No nonlinear preconditioner set");
88 PetscCall(SNESGetNPCSide(snes->npc, &npcside));
89 PetscCall(SNESGetFunctionType(snes->npc, &functype));
90 PetscCall(SNESGetNormSchedule(snes->npc, &normschedule));
91
92 /* check if the function is valid based upon how the inner solver is preconditioned */
93 if (normschedule != SNES_NORM_NONE && normschedule != SNES_NORM_INITIAL_ONLY && (npcside == PC_RIGHT || functype == SNES_FUNCTION_UNPRECONDITIONED)) {
94 PetscCall(SNESGetFunction(snes->npc, &FPC, NULL, NULL));
95 PetscCheck(FPC, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONGSTATE, "Nonlinear preconditioner has no function");
96 if (fnorm) PetscCall(VecNorm(FPC, NORM_2, fnorm));
97 PetscCall(VecCopy(FPC, F));
98 } else {
99 PetscCall(SNESGetSolution(snes->npc, &XPC));
100 PetscCheck(XPC, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONGSTATE, "Nonlinear preconditioner has no solution");
101 PetscCall(SNESComputeFunction(snes->npc, XPC, F));
102 if (fnorm) PetscCall(VecNorm(F, NORM_2, fnorm));
103 }
104 PetscFunctionReturn(PETSC_SUCCESS);
105 }
106