Date: 2021-03-03T22:27:14+00:00

Actual source code: lu.c
petsc-3.14.5 2021-03-03
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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,NULL);
     37:     PCFactorReorderForNonzeroDiagonal(pc,tol);
     38:   }
     39:   PetscOptionsTail();
     40:   return(0);
     41: }

     43: static PetscErrorCode PCSetUp_LU(PC pc)
     44: {
     45:   PetscErrorCode         ierr;
     46:   PC_LU                  *dir = (PC_LU*)pc->data;
     47:   MatSolverType          stype;
     48:   MatFactorError         err;

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

     54:   MatSetErrorIfFailure(pc->pmat,pc->erroriffailure);
     55:   if (dir->hdr.inplace) {
     56:     MatFactorType ftype;

     58:     MatGetFactorType(pc->pmat, &ftype);
     59:     if (ftype == MAT_FACTOR_NONE) {
     60:       if (dir->row && dir->col && dir->row != dir->col) {ISDestroy(&dir->row);}
     61:       ISDestroy(&dir->col);
     62:       /* This should only get the ordering if needed, but since MatGetFactor() is not called we can't know if it is needed */
     63:       MatGetOrdering(pc->pmat,((PC_Factor*)dir)->ordering,&dir->row,&dir->col);
     64:       if (dir->row) {
     65:         PetscLogObjectParent((PetscObject)pc,(PetscObject)dir->row);
     66:         PetscLogObjectParent((PetscObject)pc,(PetscObject)dir->col);
     67:       }
     68:       MatLUFactor(pc->pmat,dir->row,dir->col,&((PC_Factor*)dir)->info);
     69:       MatFactorGetError(pc->pmat,&err);
     70:       if (err) { /* Factor() fails */
     71:         pc->failedreason = (PCFailedReason)err;
     72:         return(0);
     73:       }
     74:     }
     75:     ((PC_Factor*)dir)->fact = pc->pmat;
     76:   } else {
     77:     MatInfo info;

     79:     if (!pc->setupcalled) {
     80:       PetscBool useordering;
     81:       if (!((PC_Factor*)dir)->fact) {
     82:         MatGetFactor(pc->pmat,((PC_Factor*)dir)->solvertype,MAT_FACTOR_LU,&((PC_Factor*)dir)->fact);
     83:         PetscLogObjectParent((PetscObject)pc,(PetscObject)((PC_Factor*)dir)->fact);
     84:       }
     85:       MatFactorGetUseOrdering(((PC_Factor*)dir)->fact,&useordering);
     86:       if (useordering) {
     87:         MatGetOrdering(pc->pmat,((PC_Factor*)dir)->ordering,&dir->row,&dir->col);
     88:         if (dir->nonzerosalongdiagonal) {
     89:           MatReorderForNonzeroDiagonal(pc->pmat,dir->nonzerosalongdiagonaltol,dir->row,dir->col);
     90:         }
     91:         PetscLogObjectParent((PetscObject)pc,(PetscObject)dir->row);
     92:         PetscLogObjectParent((PetscObject)pc,(PetscObject)dir->col);
     93:       }
     94:       MatLUFactorSymbolic(((PC_Factor*)dir)->fact,pc->pmat,dir->row,dir->col,&((PC_Factor*)dir)->info);
     95:       MatGetInfo(((PC_Factor*)dir)->fact,MAT_LOCAL,&info);
     96:       dir->hdr.actualfill = info.fill_ratio_needed;
     97:     } else if (pc->flag != SAME_NONZERO_PATTERN) {
     98:       PetscBool useordering;
     99:       if (!dir->hdr.reuseordering) {
    100:         MatDestroy(&((PC_Factor*)dir)->fact);
    101:         MatGetFactor(pc->pmat,((PC_Factor*)dir)->solvertype,MAT_FACTOR_LU,&((PC_Factor*)dir)->fact);
    102:         PetscLogObjectParent((PetscObject)pc,(PetscObject)((PC_Factor*)dir)->fact);
    103:         MatFactorGetUseOrdering(((PC_Factor*)dir)->fact,&useordering);
    104:         if (useordering) {
    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:           PetscLogObjectParent((PetscObject)pc,(PetscObject)dir->row);
    112:           PetscLogObjectParent((PetscObject)pc,(PetscObject)dir->col);
    113:         }
    114:       }
    115:       MatLUFactorSymbolic(((PC_Factor*)dir)->fact,pc->pmat,dir->row,dir->col,&((PC_Factor*)dir)->info);
    116:       MatGetInfo(((PC_Factor*)dir)->fact,MAT_LOCAL,&info);
    117:       dir->hdr.actualfill = info.fill_ratio_needed;
    118:     } else {
    119:       MatFactorGetError(((PC_Factor*)dir)->fact,&err);
    120:       if (err == MAT_FACTOR_NUMERIC_ZEROPIVOT) {
    121:         MatFactorClearError(((PC_Factor*)dir)->fact);
    122:         pc->failedreason = PC_NOERROR;
    123:       }
    124:     }
    125:     MatFactorGetError(((PC_Factor*)dir)->fact,&err);
    126:     if (err) { /* FactorSymbolic() fails */
    127:       pc->failedreason = (PCFailedReason)err;
    128:       return(0);
    129:     }

    131:     MatLUFactorNumeric(((PC_Factor*)dir)->fact,pc->pmat,&((PC_Factor*)dir)->info);
    132:     MatFactorGetError(((PC_Factor*)dir)->fact,&err);
    133:     if (err) { /* FactorNumeric() fails */
    134:       pc->failedreason = (PCFailedReason)err;
    135:     }

    137:   }

    139:   PCFactorGetMatSolverType(pc,&stype);
    140:   if (!stype) {
    141:     MatSolverType solverpackage;
    142:     MatFactorGetSolverType(((PC_Factor*)dir)->fact,&solverpackage);
    143:     PCFactorSetMatSolverType(pc,solverpackage);
    144:   }
    145:   return(0);
    146: }

    148: static PetscErrorCode PCReset_LU(PC pc)
    149: {
    150:   PC_LU          *dir = (PC_LU*)pc->data;

    154:   if (!dir->hdr.inplace && ((PC_Factor*)dir)->fact) {MatDestroy(&((PC_Factor*)dir)->fact);}
    155:   if (dir->row && dir->col && dir->row != dir->col) {ISDestroy(&dir->row);}
    156:   ISDestroy(&dir->col);
    157:   return(0);
    158: }

    160: static PetscErrorCode PCDestroy_LU(PC pc)
    161: {
    162:   PC_LU          *dir = (PC_LU*)pc->data;

    166:   PCReset_LU(pc);
    167:   PetscFree(((PC_Factor*)dir)->ordering);
    168:   PetscFree(((PC_Factor*)dir)->solvertype);
    169:   PetscFree(pc->data);
    170:   return(0);
    171: }

    173: static PetscErrorCode PCApply_LU(PC pc,Vec x,Vec y)
    174: {
    175:   PC_LU          *dir = (PC_LU*)pc->data;

    179:   if (dir->hdr.inplace) {
    180:     MatSolve(pc->pmat,x,y);
    181:   } else {
    182:     MatSolve(((PC_Factor*)dir)->fact,x,y);
    183:   }
    184:   return(0);
    185: }

    187: static PetscErrorCode PCMatApply_LU(PC pc,Mat X,Mat Y)
    188: {
    189:   PC_LU          *dir = (PC_LU*)pc->data;

    193:   if (dir->hdr.inplace) {
    194:     MatMatSolve(pc->pmat,X,Y);
    195:   } else {
    196:     MatMatSolve(((PC_Factor*)dir)->fact,X,Y);
    197:   }
    198:   return(0);
    199: }

    201: static PetscErrorCode PCApplyTranspose_LU(PC pc,Vec x,Vec y)
    202: {
    203:   PC_LU          *dir = (PC_LU*)pc->data;

    207:   if (dir->hdr.inplace) {
    208:     MatSolveTranspose(pc->pmat,x,y);
    209:   } else {
    210:     MatSolveTranspose(((PC_Factor*)dir)->fact,x,y);
    211:   }
    212:   return(0);
    213: }

    215: /* -----------------------------------------------------------------------------------*/

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

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

    234:    Notes:
    235:     Not all options work for all matrix formats
    236:           Run with -help to see additional options for particular matrix formats or factorization
    237:           algorithms

    239:    Level: beginner

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

    246: .seealso:  PCCreate(), PCSetType(), PCType (for list of available types), PC,
    247:            PCILU, PCCHOLESKY, PCICC, PCFactorSetReuseOrdering(), PCFactorSetReuseFill(), PCFactorGetMatrix(),
    248:            PCFactorSetFill(), PCFactorSetUseInPlace(), PCFactorSetMatOrderingType(), PCFactorSetColumnPivot(),
    249:            PCFactorSetPivotingInBlocks(),PCFactorSetShiftType(),PCFactorSetShiftAmount()
    250:            PCFactorReorderForNonzeroDiagonal()
    251: M*/

    253: PETSC_EXTERN PetscErrorCode PCCreate_LU(PC pc)
    254: {
    256:   PetscMPIInt    size;
    257:   PC_LU          *dir;

    260:   PetscNewLog(pc,&dir);
    261:   pc->data = (void*)dir;
    262:   PCFactorInitialize(pc);
    263:   ((PC_Factor*)dir)->factortype = MAT_FACTOR_LU;
    264:   dir->nonzerosalongdiagonal    = PETSC_FALSE;

    266:   ((PC_Factor*)dir)->info.fill          = 5.0;
    267:   ((PC_Factor*)dir)->info.dtcol         = 1.e-6;  /* default to pivoting; this is only thing PETSc LU supports */
    268:   ((PC_Factor*)dir)->info.shifttype     = (PetscReal)MAT_SHIFT_NONE;
    269:   dir->col                              = NULL;
    270:   dir->row                              = NULL;

    272:   MPI_Comm_size(PetscObjectComm((PetscObject)pc),&size);
    273:   if (size == 1) {
    274:     PetscStrallocpy(MATORDERINGND,(char**)&((PC_Factor*)dir)->ordering);
    275:   } else {
    276:     PetscStrallocpy(MATORDERINGNATURAL,(char**)&((PC_Factor*)dir)->ordering);
    277:   }

    279:   pc->ops->reset             = PCReset_LU;
    280:   pc->ops->destroy           = PCDestroy_LU;
    281:   pc->ops->apply             = PCApply_LU;
    282:   pc->ops->matapply          = PCMatApply_LU;
    283:   pc->ops->applytranspose    = PCApplyTranspose_LU;
    284:   pc->ops->setup             = PCSetUp_LU;
    285:   pc->ops->setfromoptions    = PCSetFromOptions_LU;
    286:   pc->ops->view              = PCView_Factor;
    287:   pc->ops->applyrichardson   = NULL;
    288:   PetscObjectComposeFunction((PetscObject)pc,"PCFactorReorderForNonzeroDiagonal_C",PCFactorReorderForNonzeroDiagonal_LU);
    289:   return(0);
    290: }