Actual source code: ilu.c
petsc-3.11.4 2019-09-28
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 PCView_ILU(PC pc,PetscViewer viewer)
74: {
78: PCView_Factor(pc,viewer);
79: return(0);
80: }
82: static PetscErrorCode PCSetUp_ILU(PC pc)
83: {
84: PetscErrorCode ierr;
85: PC_ILU *ilu = (PC_ILU*)pc->data;
86: MatInfo info;
87: PetscBool flg;
88: MatSolverType stype;
89: MatFactorError err;
92: pc->failedreason = PC_NOERROR;
93: /* ugly hack to change default, since it is not support by some matrix types */
94: if (((PC_Factor*)ilu)->info.shifttype == (PetscReal)MAT_SHIFT_NONZERO) {
95: PetscObjectTypeCompare((PetscObject)pc->pmat,MATSEQAIJ,&flg);
96: if (!flg) {
97: PetscObjectTypeCompare((PetscObject)pc->pmat,MATMPIAIJ,&flg);
98: if (!flg) {
99: ((PC_Factor*)ilu)->info.shifttype = (PetscReal)MAT_SHIFT_INBLOCKS;
100: PetscInfo(pc,"Changing shift type from NONZERO to INBLOCKS because block matrices do not support NONZERO\n");
101: }
102: }
103: }
105: MatSetErrorIfFailure(pc->pmat,pc->erroriffailure);
106: if (ilu->hdr.inplace) {
107: if (!pc->setupcalled) {
109: /* In-place factorization only makes sense with the natural ordering,
110: so we only need to get the ordering once, even if nonzero structure changes */
111: MatGetOrdering(pc->pmat,((PC_Factor*)ilu)->ordering,&ilu->row,&ilu->col);
112: if (ilu->row) {PetscLogObjectParent((PetscObject)pc,(PetscObject)ilu->row);}
113: if (ilu->col) {PetscLogObjectParent((PetscObject)pc,(PetscObject)ilu->col);}
114: }
116: /* In place ILU only makes sense with fill factor of 1.0 because
117: cannot have levels of fill */
118: ((PC_Factor*)ilu)->info.fill = 1.0;
119: ((PC_Factor*)ilu)->info.diagonal_fill = 0.0;
121: MatILUFactor(pc->pmat,ilu->row,ilu->col,&((PC_Factor*)ilu)->info);
122: MatFactorGetError(pc->pmat,&err);
123: if (err) { /* Factor() fails */
124: pc->failedreason = (PCFailedReason)err;
125: return(0);
126: }
128: ((PC_Factor*)ilu)->fact = pc->pmat;
129: /* must update the pc record of the matrix state or the PC will attempt to run PCSetUp() yet again */
130: PetscObjectStateGet((PetscObject)pc->pmat,&pc->matstate);
131: } else {
132: if (!pc->setupcalled) {
133: /* first time in so compute reordering and symbolic factorization */
134: MatGetOrdering(pc->pmat,((PC_Factor*)ilu)->ordering,&ilu->row,&ilu->col);
135: if (ilu->row) {PetscLogObjectParent((PetscObject)pc,(PetscObject)ilu->row);}
136: if (ilu->col) {PetscLogObjectParent((PetscObject)pc,(PetscObject)ilu->col);}
137: /* Remove zeros along diagonal? */
138: if (ilu->nonzerosalongdiagonal) {
139: MatReorderForNonzeroDiagonal(pc->pmat,ilu->nonzerosalongdiagonaltol,ilu->row,ilu->col);
140: }
141: if (!((PC_Factor*)ilu)->fact) {
142: MatGetFactor(pc->pmat,((PC_Factor*)ilu)->solvertype,MAT_FACTOR_ILU,&((PC_Factor*)ilu)->fact);
143: }
144: MatILUFactorSymbolic(((PC_Factor*)ilu)->fact,pc->pmat,ilu->row,ilu->col,&((PC_Factor*)ilu)->info);
145: MatGetInfo(((PC_Factor*)ilu)->fact,MAT_LOCAL,&info);
146: ilu->hdr.actualfill = info.fill_ratio_needed;
148: PetscLogObjectParent((PetscObject)pc,(PetscObject)((PC_Factor*)ilu)->fact);
149: } else if (pc->flag != SAME_NONZERO_PATTERN) {
150: if (!ilu->hdr.reuseordering) {
151: /* compute a new ordering for the ILU */
152: ISDestroy(&ilu->row);
153: ISDestroy(&ilu->col);
154: MatGetOrdering(pc->pmat,((PC_Factor*)ilu)->ordering,&ilu->row,&ilu->col);
155: if (ilu->row) {PetscLogObjectParent((PetscObject)pc,(PetscObject)ilu->row);}
156: if (ilu->col) {PetscLogObjectParent((PetscObject)pc,(PetscObject)ilu->col);}
157: /* Remove zeros along diagonal? */
158: if (ilu->nonzerosalongdiagonal) {
159: MatReorderForNonzeroDiagonal(pc->pmat,ilu->nonzerosalongdiagonaltol,ilu->row,ilu->col);
160: }
161: }
162: MatDestroy(&((PC_Factor*)ilu)->fact);
163: MatGetFactor(pc->pmat,((PC_Factor*)ilu)->solvertype,MAT_FACTOR_ILU,&((PC_Factor*)ilu)->fact);
164: MatILUFactorSymbolic(((PC_Factor*)ilu)->fact,pc->pmat,ilu->row,ilu->col,&((PC_Factor*)ilu)->info);
165: MatGetInfo(((PC_Factor*)ilu)->fact,MAT_LOCAL,&info);
166: ilu->hdr.actualfill = info.fill_ratio_needed;
168: PetscLogObjectParent((PetscObject)pc,(PetscObject)((PC_Factor*)ilu)->fact);
169: }
170: MatFactorGetError(((PC_Factor*)ilu)->fact,&err);
171: if (err) { /* FactorSymbolic() fails */
172: pc->failedreason = (PCFailedReason)err;
173: return(0);
174: }
176: MatLUFactorNumeric(((PC_Factor*)ilu)->fact,pc->pmat,&((PC_Factor*)ilu)->info);
177: MatFactorGetError(((PC_Factor*)ilu)->fact,&err);
178: if (err) { /* FactorNumeric() fails */
179: pc->failedreason = (PCFailedReason)err;
180: }
181: }
183: PCFactorGetMatSolverType(pc,&stype);
184: if (!stype) {
185: MatSolverType solverpackage;
186: MatFactorGetSolverType(((PC_Factor*)ilu)->fact,&solverpackage);
187: PCFactorSetMatSolverType(pc,solverpackage);
188: }
189: return(0);
190: }
192: static PetscErrorCode PCDestroy_ILU(PC pc)
193: {
194: PC_ILU *ilu = (PC_ILU*)pc->data;
198: PCReset_ILU(pc);
199: PetscFree(((PC_Factor*)ilu)->solvertype);
200: PetscFree(((PC_Factor*)ilu)->ordering);
201: PetscFree(pc->data);
202: return(0);
203: }
205: static PetscErrorCode PCApply_ILU(PC pc,Vec x,Vec y)
206: {
207: PC_ILU *ilu = (PC_ILU*)pc->data;
211: MatSolve(((PC_Factor*)ilu)->fact,x,y);
212: return(0);
213: }
215: static PetscErrorCode PCApplyTranspose_ILU(PC pc,Vec x,Vec y)
216: {
217: PC_ILU *ilu = (PC_ILU*)pc->data;
221: MatSolveTranspose(((PC_Factor*)ilu)->fact,x,y);
222: return(0);
223: }
225: static PetscErrorCode PCApplySymmetricLeft_ILU(PC pc,Vec x,Vec y)
226: {
228: PC_ILU *icc = (PC_ILU*)pc->data;
231: MatForwardSolve(((PC_Factor*)icc)->fact,x,y);
232: return(0);
233: }
235: static PetscErrorCode PCApplySymmetricRight_ILU(PC pc,Vec x,Vec y)
236: {
238: PC_ILU *icc = (PC_ILU*)pc->data;
241: MatBackwardSolve(((PC_Factor*)icc)->fact,x,y);
242: return(0);
243: }
245: /*MC
246: PCILU - Incomplete factorization preconditioners.
248: Options Database Keys:
249: + -pc_factor_levels <k> - number of levels of fill for ILU(k)
250: . -pc_factor_in_place - only for ILU(0) with natural ordering, reuses the space of the matrix for
251: its factorization (overwrites original matrix)
252: . -pc_factor_diagonal_fill - fill in a zero diagonal even if levels of fill indicate it wouldn't be fill
253: . -pc_factor_reuse_ordering - reuse ordering of factorized matrix from previous factorization
254: . -pc_factor_fill <nfill> - expected amount of fill in factored matrix compared to original matrix, nfill > 1
255: . -pc_factor_nonzeros_along_diagonal - reorder the matrix before factorization to remove zeros from the diagonal,
256: this decreases the chance of getting a zero pivot
257: . -pc_factor_mat_ordering_type <natural,nd,1wd,rcm,qmd> - set the row/column ordering of the factored matrix
258: - -pc_factor_pivot_in_blocks - for block ILU(k) factorization, i.e. with BAIJ matrices with block size larger
259: than 1 the diagonal blocks are factored with partial pivoting (this increases the
260: stability of the ILU factorization
262: Level: beginner
264: Concepts: incomplete factorization
266: Notes:
267: Only implemented for some matrix formats. (for parallel see PCHYPRE for hypre's ILU)
269: For BAIJ matrices this implements a point block ILU
271: The "symmetric" application of this preconditioner is not actually symmetric since L is not transpose(U)
272: even when the matrix is not symmetric since the U stores the diagonals of the factorization.
274: If you are using MATSEQAIJCUSPARSE matrices (or MATMPIAIJCUSPARESE matrices with block Jacobi), factorization
275: is never done on the GPU).
277: References:
278: + 1. - T. Dupont, R. Kendall, and H. Rachford. An approximate factorization procedure for solving
279: self adjoint elliptic difference equations. SIAM J. Numer. Anal., 5, 1968.
280: . 2. - T.A. Oliphant. An implicit numerical method for solving two dimensional timedependent diffusion problems. Quart. Appl. Math., 19, 1961.
281: - 3. - TONY F. CHAN AND HENK A. VAN DER VORST, APPROXIMATE AND INCOMPLETE FACTORIZATIONS,
282: Chapter in Parallel Numerical
283: Algorithms, edited by D. Keyes, A. Semah, V. Venkatakrishnan, ICASE/LaRC Interdisciplinary Series in
284: Science and Engineering, Kluwer.
287: .seealso: PCCreate(), PCSetType(), PCType (for list of available types), PC, PCSOR, MatOrderingType,
288: PCFactorSetZeroPivot(), PCFactorSetShiftSetType(), PCFactorSetAmount(),
289: PCFactorSetDropTolerance(),PCFactorSetFill(), PCFactorSetMatOrderingType(), PCFactorSetReuseOrdering(),
290: PCFactorSetLevels(), PCFactorSetUseInPlace(), PCFactorSetAllowDiagonalFill(), PCFactorSetPivotInBlocks(),
291: PCFactorGetAllowDiagonalFill(), PCFactorGetUseInPlace()
293: M*/
295: PETSC_EXTERN PetscErrorCode PCCreate_ILU(PC pc)
296: {
298: PC_ILU *ilu;
301: PetscNewLog(pc,&ilu);
302: pc->data = (void*)ilu;
303: PCFactorInitialize(pc);
305: ((PC_Factor*)ilu)->factortype = MAT_FACTOR_ILU;
306: ((PC_Factor*)ilu)->info.levels = 0.;
307: ((PC_Factor*)ilu)->info.fill = 1.0;
308: ilu->col = 0;
309: ilu->row = 0;
310: PetscStrallocpy(MATORDERINGNATURAL,(char**)&((PC_Factor*)ilu)->ordering);
311: ((PC_Factor*)ilu)->info.dt = PETSC_DEFAULT;
312: ((PC_Factor*)ilu)->info.dtcount = PETSC_DEFAULT;
313: ((PC_Factor*)ilu)->info.dtcol = PETSC_DEFAULT;
315: pc->ops->reset = PCReset_ILU;
316: pc->ops->destroy = PCDestroy_ILU;
317: pc->ops->apply = PCApply_ILU;
318: pc->ops->applytranspose = PCApplyTranspose_ILU;
319: pc->ops->setup = PCSetUp_ILU;
320: pc->ops->setfromoptions = PCSetFromOptions_ILU;
321: pc->ops->view = PCView_ILU;
322: pc->ops->applysymmetricleft = PCApplySymmetricLeft_ILU;
323: pc->ops->applysymmetricright = PCApplySymmetricRight_ILU;
324: pc->ops->applyrichardson = 0;
325: PetscObjectComposeFunction((PetscObject)pc,"PCFactorSetDropTolerance_C",PCFactorSetDropTolerance_ILU);
326: PetscObjectComposeFunction((PetscObject)pc,"PCFactorReorderForNonzeroDiagonal_C",PCFactorReorderForNonzeroDiagonal_ILU);
327: return(0);
328: }