Actual source code: lu.c

petsc-3.11.3 2019-06-26
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  2: /*
  3:    Defines a direct factorization preconditioner for any Mat implementation
  4:    Note: this need not be consided a preconditioner since it supplies
  5:          a direct solver.
  6: */

  8:  #include <../src/ksp/pc/impls/factor/lu/lu.h>


 11: PetscErrorCode PCFactorReorderForNonzeroDiagonal_LU(PC pc,PetscReal z)
 12: {
 13:   PC_LU *lu = (PC_LU*)pc->data;

 16:   lu->nonzerosalongdiagonal = PETSC_TRUE;
 17:   if (z == PETSC_DECIDE) lu->nonzerosalongdiagonaltol = 1.e-10;
 18:   else lu->nonzerosalongdiagonaltol = z;
 19:   return(0);
 20: }

 22: static PetscErrorCode PCSetFromOptions_LU(PetscOptionItems *PetscOptionsObject,PC pc)
 23: {
 24:   PC_LU          *lu = (PC_LU*)pc->data;
 26:   PetscBool      flg = PETSC_FALSE;
 27:   PetscReal      tol;

 30:   PetscOptionsHead(PetscOptionsObject,"LU options");
 31:   PCSetFromOptions_Factor(PetscOptionsObject,pc);

 33:   PetscOptionsName("-pc_factor_nonzeros_along_diagonal","Reorder to remove zeros from diagonal","PCFactorReorderForNonzeroDiagonal",&flg);
 34:   if (flg) {
 35:     tol  = PETSC_DECIDE;
 36:     PetscOptionsReal("-pc_factor_nonzeros_along_diagonal","Reorder to remove zeros from diagonal","PCFactorReorderForNonzeroDiagonal",lu->nonzerosalongdiagonaltol,&tol,0);
 37:     PCFactorReorderForNonzeroDiagonal(pc,tol);
 38:   }
 39:   PetscOptionsTail();
 40:   return(0);
 41: }

 43: static PetscErrorCode PCView_LU(PC pc,PetscViewer viewer)
 44: {

 48:   PCView_Factor(pc,viewer);
 49:   return(0);
 50: }

 52: static PetscErrorCode PCSetUp_LU(PC pc)
 53: {
 54:   PetscErrorCode         ierr;
 55:   PC_LU                  *dir = (PC_LU*)pc->data;
 56:   MatSolverType          stype;
 57:   MatFactorError         err;

 60:   pc->failedreason = PC_NOERROR;
 61:   if (dir->hdr.reusefill && pc->setupcalled) ((PC_Factor*)dir)->info.fill = dir->hdr.actualfill;

 63:   MatSetErrorIfFailure(pc->pmat,pc->erroriffailure);
 64:   if (dir->hdr.inplace) {
 65:     MatFactorType ftype;

 67:     MatGetFactorType(pc->pmat, &ftype);
 68:     if (ftype == MAT_FACTOR_NONE) {
 69:       if (dir->row && dir->col && dir->row != dir->col) {ISDestroy(&dir->row);}
 70:       ISDestroy(&dir->col);
 71:       MatGetOrdering(pc->pmat,((PC_Factor*)dir)->ordering,&dir->row,&dir->col);
 72:       if (dir->row) {
 73:         PetscLogObjectParent((PetscObject)pc,(PetscObject)dir->row);
 74:         PetscLogObjectParent((PetscObject)pc,(PetscObject)dir->col);
 75:       }
 76:       MatLUFactor(pc->pmat,dir->row,dir->col,&((PC_Factor*)dir)->info);
 77:       MatFactorGetError(pc->pmat,&err);
 78:       if (err) { /* Factor() fails */
 79:         pc->failedreason = (PCFailedReason)err;
 80:         return(0);
 81:       }
 82:     }
 83:     ((PC_Factor*)dir)->fact = pc->pmat;
 84:   } else {
 85:     MatInfo info;

 87:     if (!pc->setupcalled) {
 88:       MatGetOrdering(pc->pmat,((PC_Factor*)dir)->ordering,&dir->row,&dir->col);
 89:       if (dir->nonzerosalongdiagonal) {
 90:         MatReorderForNonzeroDiagonal(pc->pmat,dir->nonzerosalongdiagonaltol,dir->row,dir->col);
 91:       }
 92:       if (dir->row) {
 93:         PetscLogObjectParent((PetscObject)pc,(PetscObject)dir->row);
 94:         PetscLogObjectParent((PetscObject)pc,(PetscObject)dir->col);
 95:       }
 96:       if (!((PC_Factor*)dir)->fact) {
 97:         MatGetFactor(pc->pmat,((PC_Factor*)dir)->solvertype,MAT_FACTOR_LU,&((PC_Factor*)dir)->fact);
 98:       }
 99:       MatLUFactorSymbolic(((PC_Factor*)dir)->fact,pc->pmat,dir->row,dir->col,&((PC_Factor*)dir)->info);
100:       MatGetInfo(((PC_Factor*)dir)->fact,MAT_LOCAL,&info);
101:       dir->hdr.actualfill = info.fill_ratio_needed;
102:       PetscLogObjectParent((PetscObject)pc,(PetscObject)((PC_Factor*)dir)->fact);
103:     } else if (pc->flag != SAME_NONZERO_PATTERN) {
104:       if (!dir->hdr.reuseordering) {
105:         if (dir->row && dir->col && dir->row != dir->col) {ISDestroy(&dir->row);}
106:         ISDestroy(&dir->col);
107:         MatGetOrdering(pc->pmat,((PC_Factor*)dir)->ordering,&dir->row,&dir->col);
108:         if (dir->nonzerosalongdiagonal) {
109:           MatReorderForNonzeroDiagonal(pc->pmat,dir->nonzerosalongdiagonaltol,dir->row,dir->col);
110:         }
111:         if (dir->row) {
112:           PetscLogObjectParent((PetscObject)pc,(PetscObject)dir->row);
113:           PetscLogObjectParent((PetscObject)pc,(PetscObject)dir->col);
114:         }
115:       }
116:       MatDestroy(&((PC_Factor*)dir)->fact);
117:       MatGetFactor(pc->pmat,((PC_Factor*)dir)->solvertype,MAT_FACTOR_LU,&((PC_Factor*)dir)->fact);
118:       MatLUFactorSymbolic(((PC_Factor*)dir)->fact,pc->pmat,dir->row,dir->col,&((PC_Factor*)dir)->info);
119:       MatGetInfo(((PC_Factor*)dir)->fact,MAT_LOCAL,&info);
120:       dir->hdr.actualfill = info.fill_ratio_needed;
121:       PetscLogObjectParent((PetscObject)pc,(PetscObject)((PC_Factor*)dir)->fact);
122:     } else {
123:       MatFactorGetError(((PC_Factor*)dir)->fact,&err);
124:       if (err == MAT_FACTOR_NUMERIC_ZEROPIVOT) {
125:         MatFactorClearError(((PC_Factor*)dir)->fact);
126:         pc->failedreason = PC_NOERROR;
127:       }
128:     }
129:     MatFactorGetError(((PC_Factor*)dir)->fact,&err);
130:     if (err) { /* FactorSymbolic() fails */
131:       pc->failedreason = (PCFailedReason)err;
132:       return(0);
133:     }

135:     MatLUFactorNumeric(((PC_Factor*)dir)->fact,pc->pmat,&((PC_Factor*)dir)->info);
136:     MatFactorGetError(((PC_Factor*)dir)->fact,&err);
137:     if (err) { /* FactorNumeric() fails */
138:       pc->failedreason = (PCFailedReason)err;
139:     }

141:   }

143:   PCFactorGetMatSolverType(pc,&stype);
144:   if (!stype) {
145:     MatSolverType solverpackage;
146:     MatFactorGetSolverType(((PC_Factor*)dir)->fact,&solverpackage);
147:     PCFactorSetMatSolverType(pc,solverpackage);
148:   }
149:   return(0);
150: }

152: static PetscErrorCode PCReset_LU(PC pc)
153: {
154:   PC_LU          *dir = (PC_LU*)pc->data;

158:   if (!dir->hdr.inplace && ((PC_Factor*)dir)->fact) {MatDestroy(&((PC_Factor*)dir)->fact);}
159:   if (dir->row && dir->col && dir->row != dir->col) {ISDestroy(&dir->row);}
160:   ISDestroy(&dir->col);
161:   return(0);
162: }

164: static PetscErrorCode PCDestroy_LU(PC pc)
165: {
166:   PC_LU          *dir = (PC_LU*)pc->data;

170:   PCReset_LU(pc);
171:   PetscFree(((PC_Factor*)dir)->ordering);
172:   PetscFree(((PC_Factor*)dir)->solvertype);
173:   PetscFree(pc->data);
174:   return(0);
175: }

177: static PetscErrorCode PCApply_LU(PC pc,Vec x,Vec y)
178: {
179:   PC_LU          *dir = (PC_LU*)pc->data;

183:   if (dir->hdr.inplace) {
184:     MatSolve(pc->pmat,x,y);
185:   } else {
186:     MatSolve(((PC_Factor*)dir)->fact,x,y);
187:   }
188:   return(0);
189: }

191: static PetscErrorCode PCApplyTranspose_LU(PC pc,Vec x,Vec y)
192: {
193:   PC_LU          *dir = (PC_LU*)pc->data;

197:   if (dir->hdr.inplace) {
198:     MatSolveTranspose(pc->pmat,x,y);
199:   } else {
200:     MatSolveTranspose(((PC_Factor*)dir)->fact,x,y);
201:   }
202:   return(0);
203: }

205: /* -----------------------------------------------------------------------------------*/

207: /*MC
208:    PCLU - Uses a direct solver, based on LU factorization, as a preconditioner

210:    Options Database Keys:
211: +  -pc_factor_reuse_ordering - Activate PCFactorSetReuseOrdering()
212: .  -pc_factor_mat_solver_type - Actives PCFactorSetMatSolverType() to choose the direct solver, like superlu
213: .  -pc_factor_reuse_fill - Activates PCFactorSetReuseFill()
214: .  -pc_factor_fill <fill> - Sets fill amount
215: .  -pc_factor_in_place - Activates in-place factorization
216: .  -pc_factor_mat_ordering_type <nd,rcm,...> - Sets ordering routine
217: .  -pc_factor_pivot_in_blocks <true,false> - allow pivoting within the small blocks during factorization (may increase
218:                                          stability of factorization.
219: .  -pc_factor_shift_type <shifttype> - Sets shift type or PETSC_DECIDE for the default; use '-help' for a list of available types
220: .  -pc_factor_shift_amount <shiftamount> - Sets shift amount or PETSC_DECIDE for the default
221: -   -pc_factor_nonzeros_along_diagonal - permutes the rows and columns to try to put nonzero value along the
222:         diagonal.

224:    Notes:
225:     Not all options work for all matrix formats
226:           Run with -help to see additional options for particular matrix formats or factorization
227:           algorithms

229:    Level: beginner

231:    Concepts: LU factorization, direct solver

233:    Notes:
234:     Usually this will compute an "exact" solution in one iteration and does
235:           not need a Krylov method (i.e. you can use -ksp_type preonly, or
236:           KSPSetType(ksp,KSPPREONLY) for the Krylov method

238: .seealso:  PCCreate(), PCSetType(), PCType (for list of available types), PC,
239:            PCILU, PCCHOLESKY, PCICC, PCFactorSetReuseOrdering(), PCFactorSetReuseFill(), PCFactorGetMatrix(),
240:            PCFactorSetFill(), PCFactorSetUseInPlace(), PCFactorSetMatOrderingType(), PCFactorSetColumnPivot(),
241:            PCFactorSetPivotingInBlocks(),PCFactorSetShiftType(),PCFactorSetShiftAmount()
242:            PCFactorReorderForNonzeroDiagonal()
243: M*/

245: PETSC_EXTERN PetscErrorCode PCCreate_LU(PC pc)
246: {
248:   PetscMPIInt    size;
249:   PC_LU          *dir;

252:   PetscNewLog(pc,&dir);
253:   pc->data = (void*)dir;
254:   PCFactorInitialize(pc);
255:   ((PC_Factor*)dir)->factortype = MAT_FACTOR_LU;
256:   dir->nonzerosalongdiagonal    = PETSC_FALSE;

258:   ((PC_Factor*)dir)->info.fill          = 5.0;
259:   ((PC_Factor*)dir)->info.dtcol         = 1.e-6;  /* default to pivoting; this is only thing PETSc LU supports */
260:   ((PC_Factor*)dir)->info.shifttype     = (PetscReal)MAT_SHIFT_NONE;
261:   dir->col                              = 0;
262:   dir->row                              = 0;

264:   MPI_Comm_size(PetscObjectComm((PetscObject)pc),&size);
265:   if (size == 1) {
266:     PetscStrallocpy(MATORDERINGND,(char**)&((PC_Factor*)dir)->ordering);
267:   } else {
268:     PetscStrallocpy(MATORDERINGNATURAL,(char**)&((PC_Factor*)dir)->ordering);
269:   }

271:   pc->ops->reset             = PCReset_LU;
272:   pc->ops->destroy           = PCDestroy_LU;
273:   pc->ops->apply             = PCApply_LU;
274:   pc->ops->applytranspose    = PCApplyTranspose_LU;
275:   pc->ops->setup             = PCSetUp_LU;
276:   pc->ops->setfromoptions    = PCSetFromOptions_LU;
277:   pc->ops->view              = PCView_LU;
278:   pc->ops->applyrichardson   = 0;
279:   PetscObjectComposeFunction((PetscObject)pc,"PCFactorReorderForNonzeroDiagonal_C",PCFactorReorderForNonzeroDiagonal_LU);
280:   return(0);
281: }