Actual source code: ilu.c
petsc-3.12.5 2020-03-29
2: /*
3: Defines a ILU factorization preconditioner for any Mat implementation
4: */
5: #include <../src/ksp/pc/impls/factor/ilu/ilu.h>
7: PetscErrorCode PCFactorReorderForNonzeroDiagonal_ILU(PC pc,PetscReal z)
8: {
9: PC_ILU *ilu = (PC_ILU*)pc->data;
12: ilu->nonzerosalongdiagonal = PETSC_TRUE;
13: if (z == PETSC_DECIDE) ilu->nonzerosalongdiagonaltol = 1.e-10;
14: else ilu->nonzerosalongdiagonaltol = z;
15: return(0);
16: }
18: PetscErrorCode PCReset_ILU(PC pc)
19: {
20: PC_ILU *ilu = (PC_ILU*)pc->data;
24: if (!ilu->hdr.inplace) {MatDestroy(&((PC_Factor*)ilu)->fact);}
25: if (ilu->row && ilu->col && ilu->row != ilu->col) {ISDestroy(&ilu->row);}
26: ISDestroy(&ilu->col);
27: return(0);
28: }
30: PetscErrorCode PCFactorSetDropTolerance_ILU(PC pc,PetscReal dt,PetscReal dtcol,PetscInt dtcount)
31: {
32: PC_ILU *ilu = (PC_ILU*)pc->data;
35: if (pc->setupcalled && (((PC_Factor*)ilu)->info.dt != dt || ((PC_Factor*)ilu)->info.dtcol != dtcol || ((PC_Factor*)ilu)->info.dtcount != dtcount)) {
36: SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_SUP,"Cannot change drop tolerance after using PC");
37: }
38: ((PC_Factor*)ilu)->info.dt = dt;
39: ((PC_Factor*)ilu)->info.dtcol = dtcol;
40: ((PC_Factor*)ilu)->info.dtcount = dtcount;
41: ((PC_Factor*)ilu)->info.usedt = 1.0;
42: return(0);
43: }
45: static PetscErrorCode PCSetFromOptions_ILU(PetscOptionItems *PetscOptionsObject,PC pc)
46: {
48: PetscInt itmp;
49: PetscBool flg,set;
50: PC_ILU *ilu = (PC_ILU*)pc->data;
51: PetscReal tol;
54: PetscOptionsHead(PetscOptionsObject,"ILU Options");
55: PCSetFromOptions_Factor(PetscOptionsObject,pc);
57: PetscOptionsInt("-pc_factor_levels","levels of fill","PCFactorSetLevels",(PetscInt)((PC_Factor*)ilu)->info.levels,&itmp,&flg);
58: if (flg) ((PC_Factor*)ilu)->info.levels = itmp;
60: PetscOptionsBool("-pc_factor_diagonal_fill","Allow fill into empty diagonal entry","PCFactorSetAllowDiagonalFill",((PC_Factor*)ilu)->info.diagonal_fill ? PETSC_TRUE : PETSC_FALSE,&flg,&set);
61: if (set) ((PC_Factor*)ilu)->info.diagonal_fill = (PetscReal) flg;
62: PetscOptionsName("-pc_factor_nonzeros_along_diagonal","Reorder to remove zeros from diagonal","PCFactorReorderForNonzeroDiagonal",&flg);
63: if (flg) {
64: tol = PETSC_DECIDE;
65: PetscOptionsReal("-pc_factor_nonzeros_along_diagonal","Reorder to remove zeros from diagonal","PCFactorReorderForNonzeroDiagonal",ilu->nonzerosalongdiagonaltol,&tol,0);
66: PCFactorReorderForNonzeroDiagonal(pc,tol);
67: }
69: PetscOptionsTail();
70: return(0);
71: }
73: static PetscErrorCode PCSetUp_ILU(PC pc)
74: {
75: PetscErrorCode ierr;
76: PC_ILU *ilu = (PC_ILU*)pc->data;
77: MatInfo info;
78: PetscBool flg;
79: MatSolverType stype;
80: MatFactorError err;
83: pc->failedreason = PC_NOERROR;
84: /* ugly hack to change default, since it is not support by some matrix types */
85: if (((PC_Factor*)ilu)->info.shifttype == (PetscReal)MAT_SHIFT_NONZERO) {
86: PetscObjectTypeCompare((PetscObject)pc->pmat,MATSEQAIJ,&flg);
87: if (!flg) {
88: PetscObjectTypeCompare((PetscObject)pc->pmat,MATMPIAIJ,&flg);
89: if (!flg) {
90: ((PC_Factor*)ilu)->info.shifttype = (PetscReal)MAT_SHIFT_INBLOCKS;
91: PetscInfo(pc,"Changing shift type from NONZERO to INBLOCKS because block matrices do not support NONZERO\n");
92: }
93: }
94: }
96: MatSetErrorIfFailure(pc->pmat,pc->erroriffailure);
97: if (ilu->hdr.inplace) {
98: if (!pc->setupcalled) {
100: /* In-place factorization only makes sense with the natural ordering,
101: so we only need to get the ordering once, even if nonzero structure changes */
102: MatGetOrdering(pc->pmat,((PC_Factor*)ilu)->ordering,&ilu->row,&ilu->col);
103: if (ilu->row) {PetscLogObjectParent((PetscObject)pc,(PetscObject)ilu->row);}
104: if (ilu->col) {PetscLogObjectParent((PetscObject)pc,(PetscObject)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: MatILUFactor(pc->pmat,ilu->row,ilu->col,&((PC_Factor*)ilu)->info);
113: MatFactorGetError(pc->pmat,&err);
114: if (err) { /* Factor() fails */
115: pc->failedreason = (PCFailedReason)err;
116: return(0);
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: PetscObjectStateGet((PetscObject)pc->pmat,&pc->matstate);
122: } else {
123: if (!pc->setupcalled) {
124: /* first time in so compute reordering and symbolic factorization */
125: MatGetOrdering(pc->pmat,((PC_Factor*)ilu)->ordering,&ilu->row,&ilu->col);
126: if (ilu->row) {PetscLogObjectParent((PetscObject)pc,(PetscObject)ilu->row);}
127: if (ilu->col) {PetscLogObjectParent((PetscObject)pc,(PetscObject)ilu->col);}
128: /* Remove zeros along diagonal? */
129: if (ilu->nonzerosalongdiagonal) {
130: MatReorderForNonzeroDiagonal(pc->pmat,ilu->nonzerosalongdiagonaltol,ilu->row,ilu->col);
131: }
132: if (!((PC_Factor*)ilu)->fact) {
133: MatGetFactor(pc->pmat,((PC_Factor*)ilu)->solvertype,MAT_FACTOR_ILU,&((PC_Factor*)ilu)->fact);
134: }
135: MatILUFactorSymbolic(((PC_Factor*)ilu)->fact,pc->pmat,ilu->row,ilu->col,&((PC_Factor*)ilu)->info);
136: MatGetInfo(((PC_Factor*)ilu)->fact,MAT_LOCAL,&info);
137: ilu->hdr.actualfill = info.fill_ratio_needed;
139: PetscLogObjectParent((PetscObject)pc,(PetscObject)((PC_Factor*)ilu)->fact);
140: } else if (pc->flag != SAME_NONZERO_PATTERN) {
141: if (!ilu->hdr.reuseordering) {
142: /* compute a new ordering for the ILU */
143: ISDestroy(&ilu->row);
144: ISDestroy(&ilu->col);
145: MatGetOrdering(pc->pmat,((PC_Factor*)ilu)->ordering,&ilu->row,&ilu->col);
146: if (ilu->row) {PetscLogObjectParent((PetscObject)pc,(PetscObject)ilu->row);}
147: if (ilu->col) {PetscLogObjectParent((PetscObject)pc,(PetscObject)ilu->col);}
148: /* Remove zeros along diagonal? */
149: if (ilu->nonzerosalongdiagonal) {
150: MatReorderForNonzeroDiagonal(pc->pmat,ilu->nonzerosalongdiagonaltol,ilu->row,ilu->col);
151: }
152: }
153: MatDestroy(&((PC_Factor*)ilu)->fact);
154: MatGetFactor(pc->pmat,((PC_Factor*)ilu)->solvertype,MAT_FACTOR_ILU,&((PC_Factor*)ilu)->fact);
155: MatILUFactorSymbolic(((PC_Factor*)ilu)->fact,pc->pmat,ilu->row,ilu->col,&((PC_Factor*)ilu)->info);
156: MatGetInfo(((PC_Factor*)ilu)->fact,MAT_LOCAL,&info);
157: ilu->hdr.actualfill = info.fill_ratio_needed;
159: PetscLogObjectParent((PetscObject)pc,(PetscObject)((PC_Factor*)ilu)->fact);
160: }
161: MatFactorGetError(((PC_Factor*)ilu)->fact,&err);
162: if (err) { /* FactorSymbolic() fails */
163: pc->failedreason = (PCFailedReason)err;
164: return(0);
165: }
167: MatLUFactorNumeric(((PC_Factor*)ilu)->fact,pc->pmat,&((PC_Factor*)ilu)->info);
168: MatFactorGetError(((PC_Factor*)ilu)->fact,&err);
169: if (err) { /* FactorNumeric() fails */
170: pc->failedreason = (PCFailedReason)err;
171: }
172: }
174: PCFactorGetMatSolverType(pc,&stype);
175: if (!stype) {
176: MatSolverType solverpackage;
177: MatFactorGetSolverType(((PC_Factor*)ilu)->fact,&solverpackage);
178: PCFactorSetMatSolverType(pc,solverpackage);
179: }
180: return(0);
181: }
183: static PetscErrorCode PCDestroy_ILU(PC pc)
184: {
185: PC_ILU *ilu = (PC_ILU*)pc->data;
189: PCReset_ILU(pc);
190: PetscFree(((PC_Factor*)ilu)->solvertype);
191: PetscFree(((PC_Factor*)ilu)->ordering);
192: PetscFree(pc->data);
193: return(0);
194: }
196: static PetscErrorCode PCApply_ILU(PC pc,Vec x,Vec y)
197: {
198: PC_ILU *ilu = (PC_ILU*)pc->data;
202: MatSolve(((PC_Factor*)ilu)->fact,x,y);
203: return(0);
204: }
206: static PetscErrorCode PCApplyTranspose_ILU(PC pc,Vec x,Vec y)
207: {
208: PC_ILU *ilu = (PC_ILU*)pc->data;
212: MatSolveTranspose(((PC_Factor*)ilu)->fact,x,y);
213: return(0);
214: }
216: static PetscErrorCode PCApplySymmetricLeft_ILU(PC pc,Vec x,Vec y)
217: {
219: PC_ILU *icc = (PC_ILU*)pc->data;
222: MatForwardSolve(((PC_Factor*)icc)->fact,x,y);
223: return(0);
224: }
226: static PetscErrorCode PCApplySymmetricRight_ILU(PC pc,Vec x,Vec y)
227: {
229: PC_ILU *icc = (PC_ILU*)pc->data;
232: MatBackwardSolve(((PC_Factor*)icc)->fact,x,y);
233: return(0);
234: }
236: /*MC
237: PCILU - Incomplete factorization preconditioners.
239: Options Database Keys:
240: + -pc_factor_levels <k> - number of levels of fill for ILU(k)
241: . -pc_factor_in_place - only for ILU(0) with natural ordering, reuses the space of the matrix for
242: its factorization (overwrites original matrix)
243: . -pc_factor_diagonal_fill - fill in a zero diagonal even if levels of fill indicate it wouldn't be fill
244: . -pc_factor_reuse_ordering - reuse ordering of factorized matrix from previous factorization
245: . -pc_factor_fill <nfill> - expected amount of fill in factored matrix compared to original matrix, nfill > 1
246: . -pc_factor_nonzeros_along_diagonal - reorder the matrix before factorization to remove zeros from the diagonal,
247: this decreases the chance of getting a zero pivot
248: . -pc_factor_mat_ordering_type <natural,nd,1wd,rcm,qmd> - set the row/column ordering of the factored matrix
249: - -pc_factor_pivot_in_blocks - for block ILU(k) factorization, i.e. with BAIJ matrices with block size larger
250: than 1 the diagonal blocks are factored with partial pivoting (this increases the
251: stability of the ILU factorization
253: Level: beginner
255: Notes:
256: Only implemented for some matrix formats. (for parallel see PCHYPRE for hypre's ILU)
258: For BAIJ matrices this implements a point block ILU
260: The "symmetric" application of this preconditioner is not actually symmetric since L is not transpose(U)
261: even when the matrix is not symmetric since the U stores the diagonals of the factorization.
263: If you are using MATSEQAIJCUSPARSE matrices (or MATMPIAIJCUSPARESE matrices with block Jacobi), factorization
264: is never done on the GPU).
266: References:
267: + 1. - T. Dupont, R. Kendall, and H. Rachford. An approximate factorization procedure for solving
268: self adjoint elliptic difference equations. SIAM J. Numer. Anal., 5, 1968.
269: . 2. - T.A. Oliphant. An implicit numerical method for solving two dimensional timedependent diffusion problems. Quart. Appl. Math., 19, 1961.
270: - 3. - TONY F. CHAN AND HENK A. VAN DER VORST, APPROXIMATE AND INCOMPLETE FACTORIZATIONS,
271: Chapter in Parallel Numerical
272: Algorithms, edited by D. Keyes, A. Semah, V. Venkatakrishnan, ICASE/LaRC Interdisciplinary Series in
273: Science and Engineering, Kluwer.
276: .seealso: PCCreate(), PCSetType(), PCType (for list of available types), PC, PCSOR, MatOrderingType,
277: PCFactorSetZeroPivot(), PCFactorSetShiftSetType(), PCFactorSetAmount(),
278: PCFactorSetDropTolerance(),PCFactorSetFill(), PCFactorSetMatOrderingType(), PCFactorSetReuseOrdering(),
279: PCFactorSetLevels(), PCFactorSetUseInPlace(), PCFactorSetAllowDiagonalFill(), PCFactorSetPivotInBlocks(),
280: PCFactorGetAllowDiagonalFill(), PCFactorGetUseInPlace()
282: M*/
284: PETSC_EXTERN PetscErrorCode PCCreate_ILU(PC pc)
285: {
287: PC_ILU *ilu;
290: PetscNewLog(pc,&ilu);
291: pc->data = (void*)ilu;
292: PCFactorInitialize(pc);
294: ((PC_Factor*)ilu)->factortype = MAT_FACTOR_ILU;
295: ((PC_Factor*)ilu)->info.levels = 0.;
296: ((PC_Factor*)ilu)->info.fill = 1.0;
297: ilu->col = 0;
298: ilu->row = 0;
299: PetscStrallocpy(MATORDERINGNATURAL,(char**)&((PC_Factor*)ilu)->ordering);
300: ((PC_Factor*)ilu)->info.dt = PETSC_DEFAULT;
301: ((PC_Factor*)ilu)->info.dtcount = PETSC_DEFAULT;
302: ((PC_Factor*)ilu)->info.dtcol = PETSC_DEFAULT;
304: pc->ops->reset = PCReset_ILU;
305: pc->ops->destroy = PCDestroy_ILU;
306: pc->ops->apply = PCApply_ILU;
307: pc->ops->applytranspose = PCApplyTranspose_ILU;
308: pc->ops->setup = PCSetUp_ILU;
309: pc->ops->setfromoptions = PCSetFromOptions_ILU;
310: pc->ops->view = PCView_Factor;
311: pc->ops->applysymmetricleft = PCApplySymmetricLeft_ILU;
312: pc->ops->applysymmetricright = PCApplySymmetricRight_ILU;
313: pc->ops->applyrichardson = 0;
314: PetscObjectComposeFunction((PetscObject)pc,"PCFactorSetDropTolerance_C",PCFactorSetDropTolerance_ILU);
315: PetscObjectComposeFunction((PetscObject)pc,"PCFactorReorderForNonzeroDiagonal_C",PCFactorReorderForNonzeroDiagonal_ILU);
316: return(0);
317: }