Actual source code: lu.c
petsc-3.13.6 2020-09-29
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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 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:       MatGetOrdering(pc->pmat,((PC_Factor*)dir)->ordering,&dir->row,&dir->col);
     63:       if (dir->row) {
     64:         PetscLogObjectParent((PetscObject)pc,(PetscObject)dir->row);
     65:         PetscLogObjectParent((PetscObject)pc,(PetscObject)dir->col);
     66:       }
     67:       MatLUFactor(pc->pmat,dir->row,dir->col,&((PC_Factor*)dir)->info);
     68:       MatFactorGetError(pc->pmat,&err);
     69:       if (err) { /* Factor() fails */
     70:         pc->failedreason = (PCFailedReason)err;
     71:         return(0);
     72:       }
     73:     }
     74:     ((PC_Factor*)dir)->fact = pc->pmat;
     75:   } else {
     76:     MatInfo info;

     78:     if (!pc->setupcalled) {
     79:       MatGetOrdering(pc->pmat,((PC_Factor*)dir)->ordering,&dir->row,&dir->col);
     80:       if (dir->nonzerosalongdiagonal) {
     81:         MatReorderForNonzeroDiagonal(pc->pmat,dir->nonzerosalongdiagonaltol,dir->row,dir->col);
     82:       }
     83:       if (dir->row) {
     84:         PetscLogObjectParent((PetscObject)pc,(PetscObject)dir->row);
     85:         PetscLogObjectParent((PetscObject)pc,(PetscObject)dir->col);
     86:       }
     87:       if (!((PC_Factor*)dir)->fact) {
     88:         MatGetFactor(pc->pmat,((PC_Factor*)dir)->solvertype,MAT_FACTOR_LU,&((PC_Factor*)dir)->fact);
     89:       }
     90:       MatLUFactorSymbolic(((PC_Factor*)dir)->fact,pc->pmat,dir->row,dir->col,&((PC_Factor*)dir)->info);
     91:       MatGetInfo(((PC_Factor*)dir)->fact,MAT_LOCAL,&info);
     92:       dir->hdr.actualfill = info.fill_ratio_needed;
     93:       PetscLogObjectParent((PetscObject)pc,(PetscObject)((PC_Factor*)dir)->fact);
     94:     } else if (pc->flag != SAME_NONZERO_PATTERN) {
     95:       if (!dir->hdr.reuseordering) {
     96:         if (dir->row && dir->col && dir->row != dir->col) {ISDestroy(&dir->row);}
     97:         ISDestroy(&dir->col);
     98:         MatGetOrdering(pc->pmat,((PC_Factor*)dir)->ordering,&dir->row,&dir->col);
     99:         if (dir->nonzerosalongdiagonal) {
    100:           MatReorderForNonzeroDiagonal(pc->pmat,dir->nonzerosalongdiagonaltol,dir->row,dir->col);
    101:         }
    102:         if (dir->row) {
    103:           PetscLogObjectParent((PetscObject)pc,(PetscObject)dir->row);
    104:           PetscLogObjectParent((PetscObject)pc,(PetscObject)dir->col);
    105:         }
    106:       }
    107:       MatDestroy(&((PC_Factor*)dir)->fact);
    108:       MatGetFactor(pc->pmat,((PC_Factor*)dir)->solvertype,MAT_FACTOR_LU,&((PC_Factor*)dir)->fact);
    109:       MatLUFactorSymbolic(((PC_Factor*)dir)->fact,pc->pmat,dir->row,dir->col,&((PC_Factor*)dir)->info);
    110:       MatGetInfo(((PC_Factor*)dir)->fact,MAT_LOCAL,&info);
    111:       dir->hdr.actualfill = info.fill_ratio_needed;
    112:       PetscLogObjectParent((PetscObject)pc,(PetscObject)((PC_Factor*)dir)->fact);
    113:     } else {
    114:       MatFactorGetError(((PC_Factor*)dir)->fact,&err);
    115:       if (err == MAT_FACTOR_NUMERIC_ZEROPIVOT) {
    116:         MatFactorClearError(((PC_Factor*)dir)->fact);
    117:         pc->failedreason = PC_NOERROR;
    118:       }
    119:     }
    120:     MatFactorGetError(((PC_Factor*)dir)->fact,&err);
    121:     if (err) { /* FactorSymbolic() fails */
    122:       pc->failedreason = (PCFailedReason)err;
    123:       return(0);
    124:     }

    126:     MatLUFactorNumeric(((PC_Factor*)dir)->fact,pc->pmat,&((PC_Factor*)dir)->info);
    127:     MatFactorGetError(((PC_Factor*)dir)->fact,&err);
    128:     if (err) { /* FactorNumeric() fails */
    129:       pc->failedreason = (PCFailedReason)err;
    130:     }

    132:   }

    134:   PCFactorGetMatSolverType(pc,&stype);
    135:   if (!stype) {
    136:     MatSolverType solverpackage;
    137:     MatFactorGetSolverType(((PC_Factor*)dir)->fact,&solverpackage);
    138:     PCFactorSetMatSolverType(pc,solverpackage);
    139:   }
    140:   return(0);
    141: }

    143: static PetscErrorCode PCReset_LU(PC pc)
    144: {
    145:   PC_LU          *dir = (PC_LU*)pc->data;

    149:   if (!dir->hdr.inplace && ((PC_Factor*)dir)->fact) {MatDestroy(&((PC_Factor*)dir)->fact);}
    150:   if (dir->row && dir->col && dir->row != dir->col) {ISDestroy(&dir->row);}
    151:   ISDestroy(&dir->col);
    152:   return(0);
    153: }

    155: static PetscErrorCode PCDestroy_LU(PC pc)
    156: {
    157:   PC_LU          *dir = (PC_LU*)pc->data;

    161:   PCReset_LU(pc);
    162:   PetscFree(((PC_Factor*)dir)->ordering);
    163:   PetscFree(((PC_Factor*)dir)->solvertype);
    164:   PetscFree(pc->data);
    165:   return(0);
    166: }

    168: static PetscErrorCode PCApply_LU(PC pc,Vec x,Vec y)
    169: {
    170:   PC_LU          *dir = (PC_LU*)pc->data;

    174:   if (dir->hdr.inplace) {
    175:     MatSolve(pc->pmat,x,y);
    176:   } else {
    177:     MatSolve(((PC_Factor*)dir)->fact,x,y);
    178:   }
    179:   return(0);
    180: }

    182: static PetscErrorCode PCApplyTranspose_LU(PC pc,Vec x,Vec y)
    183: {
    184:   PC_LU          *dir = (PC_LU*)pc->data;

    188:   if (dir->hdr.inplace) {
    189:     MatSolveTranspose(pc->pmat,x,y);
    190:   } else {
    191:     MatSolveTranspose(((PC_Factor*)dir)->fact,x,y);
    192:   }
    193:   return(0);
    194: }

    196: /* -----------------------------------------------------------------------------------*/

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

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

    215:    Notes:
    216:     Not all options work for all matrix formats
    217:           Run with -help to see additional options for particular matrix formats or factorization
    218:           algorithms

    220:    Level: beginner

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

    227: .seealso:  PCCreate(), PCSetType(), PCType (for list of available types), PC,
    228:            PCILU, PCCHOLESKY, PCICC, PCFactorSetReuseOrdering(), PCFactorSetReuseFill(), PCFactorGetMatrix(),
    229:            PCFactorSetFill(), PCFactorSetUseInPlace(), PCFactorSetMatOrderingType(), PCFactorSetColumnPivot(),
    230:            PCFactorSetPivotingInBlocks(),PCFactorSetShiftType(),PCFactorSetShiftAmount()
    231:            PCFactorReorderForNonzeroDiagonal()
    232: M*/

    234: PETSC_EXTERN PetscErrorCode PCCreate_LU(PC pc)
    235: {
    237:   PetscMPIInt    size;
    238:   PC_LU          *dir;

    241:   PetscNewLog(pc,&dir);
    242:   pc->data = (void*)dir;
    243:   PCFactorInitialize(pc);
    244:   ((PC_Factor*)dir)->factortype = MAT_FACTOR_LU;
    245:   dir->nonzerosalongdiagonal    = PETSC_FALSE;

    247:   ((PC_Factor*)dir)->info.fill          = 5.0;
    248:   ((PC_Factor*)dir)->info.dtcol         = 1.e-6;  /* default to pivoting; this is only thing PETSc LU supports */
    249:   ((PC_Factor*)dir)->info.shifttype     = (PetscReal)MAT_SHIFT_NONE;
    250:   dir->col                              = 0;
    251:   dir->row                              = 0;

    253:   MPI_Comm_size(PetscObjectComm((PetscObject)pc),&size);
    254:   if (size == 1) {
    255:     PetscStrallocpy(MATORDERINGND,(char**)&((PC_Factor*)dir)->ordering);
    256:   } else {
    257:     PetscStrallocpy(MATORDERINGNATURAL,(char**)&((PC_Factor*)dir)->ordering);
    258:   }

    260:   pc->ops->reset             = PCReset_LU;
    261:   pc->ops->destroy           = PCDestroy_LU;
    262:   pc->ops->apply             = PCApply_LU;
    263:   pc->ops->applytranspose    = PCApplyTranspose_LU;
    264:   pc->ops->setup             = PCSetUp_LU;
    265:   pc->ops->setfromoptions    = PCSetFromOptions_LU;
    266:   pc->ops->view              = PCView_Factor;
    267:   pc->ops->applyrichardson   = 0;
    268:   PetscObjectComposeFunction((PetscObject)pc,"PCFactorReorderForNonzeroDiagonal_C",PCFactorReorderForNonzeroDiagonal_LU);
    269:   return(0);
    270: }