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 @*/ 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 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 and its norm from a nonlinear preconditioner after `SNESSolve()` has been called on that `SNES` 62 63 Collective 64 65 Input Parameter: 66 . snes - the `SNES` context 67 68 Output Parameters: 69 + F - function vector 70 - fnorm - the norm of `F` 71 72 Level: developer 73 74 .seealso: [](ch_snes), `SNES`, `SNESGetNPC()`, `SNESSetNPC()`, `SNESComputeFunction()`, `SNESApplyNPC()`, `SNESSolve()` 75 @*/ 76 PetscErrorCode SNESGetNPCFunction(SNES snes, Vec F, PetscReal *fnorm) 77 { 78 PCSide npcside; 79 SNESFunctionType functype; 80 SNESNormSchedule normschedule; 81 Vec FPC, XPC; 82 83 PetscFunctionBegin; 84 PetscValidHeaderSpecific(snes, SNES_CLASSID, 1); 85 if (fnorm) PetscAssertPointer(fnorm, 3); 86 PetscCheck(snes->npc, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONGSTATE, "No nonlinear preconditioner set"); 87 PetscCall(SNESGetNPCSide(snes->npc, &npcside)); 88 PetscCall(SNESGetFunctionType(snes->npc, &functype)); 89 PetscCall(SNESGetNormSchedule(snes->npc, &normschedule)); 90 91 /* check if the function is valid based upon how the inner solver is preconditioned */ 92 if (normschedule != SNES_NORM_NONE && normschedule != SNES_NORM_INITIAL_ONLY && (npcside == PC_RIGHT || functype == SNES_FUNCTION_UNPRECONDITIONED)) { 93 PetscCall(SNESGetFunction(snes->npc, &FPC, NULL, NULL)); 94 PetscCheck(FPC, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONGSTATE, "Nonlinear preconditioner has no function"); 95 if (fnorm) PetscCall(VecNorm(FPC, NORM_2, fnorm)); 96 PetscCall(VecCopy(FPC, F)); 97 } else { 98 PetscCall(SNESGetSolution(snes->npc, &XPC)); 99 PetscCheck(XPC, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONGSTATE, "Nonlinear preconditioner has no solution"); 100 PetscCall(SNESComputeFunction(snes->npc, XPC, F)); 101 if (fnorm) PetscCall(VecNorm(F, NORM_2, fnorm)); 102 } 103 PetscFunctionReturn(PETSC_SUCCESS); 104 } 105