Actual source code: ilu.c
1: /*
2: Defines a ILU factorization preconditioner for any Mat implementation
3: */
4: #include <../src/ksp/pc/impls/factor/ilu/ilu.h>
6: static PetscErrorCode PCFactorReorderForNonzeroDiagonal_ILU(PC pc, PetscReal z)
7: {
8: PC_ILU *ilu = (PC_ILU *)pc->data;
10: PetscFunctionBegin;
11: ilu->nonzerosalongdiagonal = PETSC_TRUE;
12: if (z == (PetscReal)PETSC_DECIDE) ilu->nonzerosalongdiagonaltol = 1.e-10;
13: else ilu->nonzerosalongdiagonaltol = z;
14: PetscFunctionReturn(PETSC_SUCCESS);
15: }
17: static PetscErrorCode PCReset_ILU(PC pc)
18: {
19: PC_ILU *ilu = (PC_ILU *)pc->data;
21: PetscFunctionBegin;
22: if (!ilu->hdr.inplace) PetscCall(MatDestroy(&((PC_Factor *)ilu)->fact));
23: if (ilu->row && ilu->col && ilu->row != ilu->col) PetscCall(ISDestroy(&ilu->row));
24: PetscCall(ISDestroy(&ilu->col));
25: PetscFunctionReturn(PETSC_SUCCESS);
26: }
28: PetscErrorCode PCFactorSetDropTolerance_ILU(PC pc, PetscReal dt, PetscReal dtcol, PetscInt dtcount)
29: {
30: PC_ILU *ilu = (PC_ILU *)pc->data;
32: PetscFunctionBegin;
33: if (pc->setupcalled && (((PC_Factor *)ilu)->info.dt != dt || ((PC_Factor *)ilu)->info.dtcol != dtcol || ((PC_Factor *)ilu)->info.dtcount != dtcount)) {
34: SETERRQ(PetscObjectComm((PetscObject)pc), PETSC_ERR_SUP, "Cannot change drop tolerance after using PC");
35: }
36: ((PC_Factor *)ilu)->info.dt = dt;
37: ((PC_Factor *)ilu)->info.dtcol = dtcol;
38: ((PC_Factor *)ilu)->info.dtcount = dtcount;
39: ((PC_Factor *)ilu)->info.usedt = 1.0;
40: PetscFunctionReturn(PETSC_SUCCESS);
41: }
43: static PetscErrorCode PCSetFromOptions_ILU(PC pc, PetscOptionItems *PetscOptionsObject)
44: {
45: PetscInt itmp;
46: PetscBool flg, set;
47: PC_ILU *ilu = (PC_ILU *)pc->data;
48: PetscReal tol;
50: PetscFunctionBegin;
51: PetscOptionsHeadBegin(PetscOptionsObject, "ILU Options");
52: PetscCall(PCSetFromOptions_Factor(pc, PetscOptionsObject));
54: PetscCall(PetscOptionsInt("-pc_factor_levels", "levels of fill", "PCFactorSetLevels", (PetscInt)((PC_Factor *)ilu)->info.levels, &itmp, &flg));
55: if (flg) ((PC_Factor *)ilu)->info.levels = itmp;
57: PetscCall(PetscOptionsBool("-pc_factor_diagonal_fill", "Allow fill into empty diagonal entry", "PCFactorSetAllowDiagonalFill", ((PC_Factor *)ilu)->info.diagonal_fill ? PETSC_TRUE : PETSC_FALSE, &flg, &set));
58: if (set) ((PC_Factor *)ilu)->info.diagonal_fill = (PetscReal)flg;
59: PetscCall(PetscOptionsName("-pc_factor_nonzeros_along_diagonal", "Reorder to remove zeros from diagonal", "PCFactorReorderForNonzeroDiagonal", &flg));
60: if (flg) {
61: tol = PETSC_DECIDE;
62: PetscCall(PetscOptionsReal("-pc_factor_nonzeros_along_diagonal", "Reorder to remove zeros from diagonal", "PCFactorReorderForNonzeroDiagonal", ilu->nonzerosalongdiagonaltol, &tol, NULL));
63: PetscCall(PCFactorReorderForNonzeroDiagonal(pc, tol));
64: }
66: PetscOptionsHeadEnd();
67: PetscFunctionReturn(PETSC_SUCCESS);
68: }
70: static PetscErrorCode PCSetUp_ILU(PC pc)
71: {
72: PC_ILU *ilu = (PC_ILU *)pc->data;
73: MatInfo info;
74: PetscBool flg;
75: MatSolverType stype;
76: MatFactorError err;
77: const char *prefix;
79: PetscFunctionBegin;
80: pc->failedreason = PC_NOERROR;
81: /* ugly hack to change default, since it is not support by some matrix types */
82: if (((PC_Factor *)ilu)->info.shifttype == (PetscReal)MAT_SHIFT_NONZERO) {
83: PetscCall(PetscObjectTypeCompare((PetscObject)pc->pmat, MATSEQAIJ, &flg));
84: if (!flg) {
85: PetscCall(PetscObjectTypeCompare((PetscObject)pc->pmat, MATMPIAIJ, &flg));
86: if (!flg) {
87: ((PC_Factor *)ilu)->info.shifttype = (PetscReal)MAT_SHIFT_INBLOCKS;
88: PetscCall(PetscInfo(pc, "Changing shift type from NONZERO to INBLOCKS because block matrices do not support NONZERO\n"));
89: }
90: }
91: }
93: PetscCall(PCGetOptionsPrefix(pc, &prefix));
94: PetscCall(MatSetOptionsPrefixFactor(pc->pmat, prefix));
96: PetscCall(MatSetErrorIfFailure(pc->pmat, pc->erroriffailure));
97: if (ilu->hdr.inplace) {
98: if (!pc->setupcalled) {
99: /* In-place factorization only makes sense with the natural ordering,
100: so we only need to get the ordering once, even if nonzero structure changes */
101: /* Should not get the ordering if the factorization routine does not use it, but do not yet have access to the factor matrix */
102: PetscCall(PCFactorSetDefaultOrdering_Factor(pc));
103: PetscCall(MatDestroy(&((PC_Factor *)ilu)->fact));
104: PetscCall(MatGetOrdering(pc->pmat, ((PC_Factor *)ilu)->ordering, &ilu->row, &ilu->col));
105: }
107: /* In place ILU only makes sense with fill factor of 1.0 because
108: cannot have levels of fill */
109: ((PC_Factor *)ilu)->info.fill = 1.0;
110: ((PC_Factor *)ilu)->info.diagonal_fill = 0.0;
112: PetscCall(MatILUFactor(pc->pmat, ilu->row, ilu->col, &((PC_Factor *)ilu)->info));
113: PetscCall(MatFactorGetError(pc->pmat, &err));
114: if (err) { /* Factor() fails */
115: pc->failedreason = (PCFailedReason)err;
116: PetscFunctionReturn(PETSC_SUCCESS);
117: }
119: ((PC_Factor *)ilu)->fact = pc->pmat;
120: /* must update the pc record of the matrix state or the PC will attempt to run PCSetUp() yet again */
121: PetscCall(PetscObjectStateGet((PetscObject)pc->pmat, &pc->matstate));
122: } else {
123: if (!pc->setupcalled) {
124: /* first time in so compute reordering and symbolic factorization */
125: PetscBool canuseordering;
127: PetscCall(PCFactorSetUpMatSolverType(pc));
128: PetscCall(MatFactorGetCanUseOrdering(((PC_Factor *)ilu)->fact, &canuseordering));
129: if (canuseordering) {
130: PetscCall(PCFactorSetDefaultOrdering_Factor(pc));
131: PetscCall(MatGetOrdering(pc->pmat, ((PC_Factor *)ilu)->ordering, &ilu->row, &ilu->col));
132: /* Remove zeros along diagonal? */
133: if (ilu->nonzerosalongdiagonal) PetscCall(MatReorderForNonzeroDiagonal(pc->pmat, ilu->nonzerosalongdiagonaltol, ilu->row, ilu->col));
134: }
135: PetscCall(MatILUFactorSymbolic(((PC_Factor *)ilu)->fact, pc->pmat, ilu->row, ilu->col, &((PC_Factor *)ilu)->info));
136: PetscCall(MatGetInfo(((PC_Factor *)ilu)->fact, MAT_LOCAL, &info));
137: ilu->hdr.actualfill = info.fill_ratio_needed;
138: } else if (pc->flag != SAME_NONZERO_PATTERN) {
139: if (!ilu->hdr.reuseordering) {
140: PetscBool canuseordering;
142: PetscCall(MatDestroy(&((PC_Factor *)ilu)->fact));
143: PetscCall(PCFactorSetUpMatSolverType(pc));
144: PetscCall(MatFactorGetCanUseOrdering(((PC_Factor *)ilu)->fact, &canuseordering));
145: if (canuseordering) {
146: /* compute a new ordering for the ILU */
147: PetscCall(ISDestroy(&ilu->row));
148: PetscCall(ISDestroy(&ilu->col));
149: PetscCall(PCFactorSetDefaultOrdering_Factor(pc));
150: PetscCall(MatGetOrdering(pc->pmat, ((PC_Factor *)ilu)->ordering, &ilu->row, &ilu->col));
151: /* Remove zeros along diagonal? */
152: if (ilu->nonzerosalongdiagonal) PetscCall(MatReorderForNonzeroDiagonal(pc->pmat, ilu->nonzerosalongdiagonaltol, ilu->row, ilu->col));
153: }
154: }
155: PetscCall(MatILUFactorSymbolic(((PC_Factor *)ilu)->fact, pc->pmat, ilu->row, ilu->col, &((PC_Factor *)ilu)->info));
156: PetscCall(MatGetInfo(((PC_Factor *)ilu)->fact, MAT_LOCAL, &info));
157: ilu->hdr.actualfill = info.fill_ratio_needed;
158: }
159: PetscCall(MatFactorGetError(((PC_Factor *)ilu)->fact, &err));
160: if (err) { /* FactorSymbolic() fails */
161: pc->failedreason = (PCFailedReason)err;
162: PetscFunctionReturn(PETSC_SUCCESS);
163: }
165: PetscCall(MatLUFactorNumeric(((PC_Factor *)ilu)->fact, pc->pmat, &((PC_Factor *)ilu)->info));
166: PetscCall(MatFactorGetError(((PC_Factor *)ilu)->fact, &err));
167: if (err) { /* FactorNumeric() fails */
168: pc->failedreason = (PCFailedReason)err;
169: }
170: }
172: PetscCall(PCFactorGetMatSolverType(pc, &stype));
173: if (!stype) {
174: MatSolverType solverpackage;
175: PetscCall(MatFactorGetSolverType(((PC_Factor *)ilu)->fact, &solverpackage));
176: PetscCall(PCFactorSetMatSolverType(pc, solverpackage));
177: }
178: PetscFunctionReturn(PETSC_SUCCESS);
179: }
181: static PetscErrorCode PCDestroy_ILU(PC pc)
182: {
183: PC_ILU *ilu = (PC_ILU *)pc->data;
185: PetscFunctionBegin;
186: PetscCall(PCReset_ILU(pc));
187: PetscCall(PetscFree(((PC_Factor *)ilu)->solvertype));
188: PetscCall(PetscFree(((PC_Factor *)ilu)->ordering));
189: PetscCall(PetscFree(pc->data));
190: PetscCall(PCFactorClearComposedFunctions(pc));
191: PetscFunctionReturn(PETSC_SUCCESS);
192: }
194: static PetscErrorCode PCApply_ILU(PC pc, Vec x, Vec y)
195: {
196: PC_ILU *ilu = (PC_ILU *)pc->data;
198: PetscFunctionBegin;
199: PetscCall(MatSolve(((PC_Factor *)ilu)->fact, x, y));
200: PetscFunctionReturn(PETSC_SUCCESS);
201: }
203: static PetscErrorCode PCMatApply_ILU(PC pc, Mat X, Mat Y)
204: {
205: PC_ILU *ilu = (PC_ILU *)pc->data;
207: PetscFunctionBegin;
208: PetscCall(MatMatSolve(((PC_Factor *)ilu)->fact, X, Y));
209: PetscFunctionReturn(PETSC_SUCCESS);
210: }
212: static PetscErrorCode PCApplyTranspose_ILU(PC pc, Vec x, Vec y)
213: {
214: PC_ILU *ilu = (PC_ILU *)pc->data;
216: PetscFunctionBegin;
217: PetscCall(MatSolveTranspose(((PC_Factor *)ilu)->fact, x, y));
218: PetscFunctionReturn(PETSC_SUCCESS);
219: }
221: static PetscErrorCode PCApplySymmetricLeft_ILU(PC pc, Vec x, Vec y)
222: {
223: PC_ILU *icc = (PC_ILU *)pc->data;
225: PetscFunctionBegin;
226: PetscCall(MatForwardSolve(((PC_Factor *)icc)->fact, x, y));
227: PetscFunctionReturn(PETSC_SUCCESS);
228: }
230: static PetscErrorCode PCApplySymmetricRight_ILU(PC pc, Vec x, Vec y)
231: {
232: PC_ILU *icc = (PC_ILU *)pc->data;
234: PetscFunctionBegin;
235: PetscCall(MatBackwardSolve(((PC_Factor *)icc)->fact, x, y));
236: PetscFunctionReturn(PETSC_SUCCESS);
237: }
239: /*MC
240: PCILU - Incomplete factorization preconditioners {cite}`dupont1968approximate`, {cite}`oliphant1961implicit`, {cite}`chan1997approximate`
242: Options Database Keys:
243: + -pc_factor_levels <k> - number of levels of fill for ILU(k)
244: . -pc_factor_in_place - only for ILU(0) with natural ordering, reuses the space of the matrix for
245: its factorization (overwrites original matrix)
246: . -pc_factor_diagonal_fill - fill in a zero diagonal even if levels of fill indicate it wouldn't be fill
247: . -pc_factor_reuse_ordering - reuse ordering of factorized matrix from previous factorization
248: . -pc_factor_fill <nfill> - expected amount of fill in factored matrix compared to original matrix, nfill > 1
249: . -pc_factor_nonzeros_along_diagonal - reorder the matrix before factorization to remove zeros from the diagonal,
250: this decreases the chance of getting a zero pivot
251: . -pc_factor_mat_ordering_type <natural,nd,1wd,rcm,qmd> - set the row/column ordering of the factored matrix
252: - -pc_factor_pivot_in_blocks - for block ILU(k) factorization, i.e. with `MATBAIJ` matrices with block size larger
253: than 1 the diagonal blocks are factored with partial pivoting (this increases the
254: stability of the ILU factorization
256: Level: beginner
258: Notes:
259: Only implemented for some matrix format and sequential. For parallel see `PCHYPRE` for hypre's ILU
261: For `MATSEQBAIJ` matrices this implements a point block ILU
263: The "symmetric" application of this preconditioner is not actually symmetric since L is not transpose(U)
264: even when the matrix is not symmetric since the U stores the diagonals of the factorization.
266: If you are using `MATSEQAIJCUSPARSE` matrices (or `MATMPIAIJCUSPARSE` matrices with block Jacobi), factorization
267: is never done on the GPU).
269: .seealso: [](ch_ksp), `PCCreate()`, `PCSetType()`, `PCType`, `PC`, `PCSOR`, `MatOrderingType`, `PCLU`, `PCICC`, `PCCHOLESKY`,
270: `PCFactorSetZeroPivot()`, `PCFactorSetShiftSetType()`, `PCFactorSetAmount()`,
271: `PCFactorSetDropTolerance()`, `PCFactorSetFill()`, `PCFactorSetMatOrderingType()`, `PCFactorSetReuseOrdering()`,
272: `PCFactorSetLevels()`, `PCFactorSetUseInPlace()`, `PCFactorSetAllowDiagonalFill()`, `PCFactorSetPivotInBlocks()`,
273: `PCFactorGetAllowDiagonalFill()`, `PCFactorGetUseInPlace()`
274: M*/
276: PETSC_EXTERN PetscErrorCode PCCreate_ILU(PC pc)
277: {
278: PC_ILU *ilu;
280: PetscFunctionBegin;
281: PetscCall(PetscNew(&ilu));
282: pc->data = (void *)ilu;
283: PetscCall(PCFactorInitialize(pc, MAT_FACTOR_ILU));
285: ((PC_Factor *)ilu)->info.levels = 0.;
286: ((PC_Factor *)ilu)->info.fill = 1.0;
287: ilu->col = NULL;
288: ilu->row = NULL;
289: ((PC_Factor *)ilu)->info.dt = PETSC_DEFAULT;
290: ((PC_Factor *)ilu)->info.dtcount = PETSC_DEFAULT;
291: ((PC_Factor *)ilu)->info.dtcol = PETSC_DEFAULT;
293: pc->ops->reset = PCReset_ILU;
294: pc->ops->destroy = PCDestroy_ILU;
295: pc->ops->apply = PCApply_ILU;
296: pc->ops->matapply = PCMatApply_ILU;
297: pc->ops->applytranspose = PCApplyTranspose_ILU;
298: pc->ops->setup = PCSetUp_ILU;
299: pc->ops->setfromoptions = PCSetFromOptions_ILU;
300: pc->ops->view = PCView_Factor;
301: pc->ops->applysymmetricleft = PCApplySymmetricLeft_ILU;
302: pc->ops->applysymmetricright = PCApplySymmetricRight_ILU;
303: pc->ops->applyrichardson = NULL;
304: PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCFactorSetDropTolerance_C", PCFactorSetDropTolerance_ILU));
305: PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCFactorReorderForNonzeroDiagonal_C", PCFactorReorderForNonzeroDiagonal_ILU));
306: PetscFunctionReturn(PETSC_SUCCESS);
307: }