Date: 2015-10-02T22:18:22+00:00

Actual source code: pbjacobi.c
petsc-3.6.2 2015-10-02
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      2: /*
      3:    Include files needed for the PBJacobi preconditioner:
      4:      pcimpl.h - private include file intended for use by all preconditioners
      5: */

      7: #include <petsc/private/matimpl.h>
      8: #include <petsc/private/pcimpl.h>   /*I "petscpc.h" I*/

     10: /*
     11:    Private context (data structure) for the PBJacobi preconditioner.
     12: */
     13: typedef struct {
     14:   const MatScalar *diag;
     15:   PetscInt        bs,mbs;
     16: } PC_PBJacobi;

     21: static PetscErrorCode PCApply_PBJacobi_1(PC pc,Vec x,Vec y)
     22: {
     23:   PC_PBJacobi       *jac = (PC_PBJacobi*)pc->data;
     24:   PetscErrorCode    ierr;
     25:   PetscInt          i,m = jac->mbs;
     26:   const MatScalar   *diag = jac->diag;
     27:   const PetscScalar *xx;
     28:   PetscScalar       *yy;

     31:   VecGetArrayRead(x,&xx);
     32:   VecGetArray(y,&yy);
     33:   for (i=0; i<m; i++) yy[i] = diag[i]*xx[i];
     34:   VecRestoreArrayRead(x,&xx);
     35:   VecRestoreArray(y,&yy);
     36:   PetscLogFlops(2.0*m);
     37:   return(0);
     38: }

     42: static PetscErrorCode PCApply_PBJacobi_2(PC pc,Vec x,Vec y)
     43: {
     44:   PC_PBJacobi     *jac = (PC_PBJacobi*)pc->data;
     45:   PetscErrorCode  ierr;
     46:   PetscInt        i,m = jac->mbs;
     47:   const MatScalar *diag = jac->diag;
     48:   PetscScalar     x0,x1,*yy;
     49:   const PetscScalar *xx;

     52:   VecGetArrayRead(x,&xx);
     53:   VecGetArray(y,&yy);
     54:   for (i=0; i<m; i++) {
     55:     x0        = xx[2*i]; x1 = xx[2*i+1];
     56:     yy[2*i]   = diag[0]*x0 + diag[2]*x1;
     57:     yy[2*i+1] = diag[1]*x0 + diag[3]*x1;
     58:     diag     += 4;
     59:   }
     60:   VecRestoreArrayRead(x,&xx);
     61:   VecRestoreArray(y,&yy);
     62:   PetscLogFlops(6.0*m);
     63:   return(0);
     64: }
     67: static PetscErrorCode PCApply_PBJacobi_3(PC pc,Vec x,Vec y)
     68: {
     69:   PC_PBJacobi     *jac = (PC_PBJacobi*)pc->data;
     70:   PetscErrorCode  ierr;
     71:   PetscInt        i,m = jac->mbs;
     72:   const MatScalar *diag = jac->diag;
     73:   PetscScalar     x0,x1,x2,*yy;
     74:   const PetscScalar *xx;

     77:   VecGetArrayRead(x,&xx);
     78:   VecGetArray(y,&yy);
     79:   for (i=0; i<m; i++) {
     80:     x0 = xx[3*i]; x1 = xx[3*i+1]; x2 = xx[3*i+2];

     82:     yy[3*i]   = diag[0]*x0 + diag[3]*x1 + diag[6]*x2;
     83:     yy[3*i+1] = diag[1]*x0 + diag[4]*x1 + diag[7]*x2;
     84:     yy[3*i+2] = diag[2]*x0 + diag[5]*x1 + diag[8]*x2;
     85:     diag     += 9;
     86:   }
     87:   VecRestoreArrayRead(x,&xx);
     88:   VecRestoreArray(y,&yy);
     89:   PetscLogFlops(15.0*m);
     90:   return(0);
     91: }
     94: static PetscErrorCode PCApply_PBJacobi_4(PC pc,Vec x,Vec y)
     95: {
     96:   PC_PBJacobi     *jac = (PC_PBJacobi*)pc->data;
     97:   PetscErrorCode  ierr;
     98:   PetscInt        i,m = jac->mbs;
     99:   const MatScalar *diag = jac->diag;
    100:   PetscScalar     x0,x1,x2,x3,*yy;
    101:   const PetscScalar *xx;

    104:   VecGetArrayRead(x,&xx);
    105:   VecGetArray(y,&yy);
    106:   for (i=0; i<m; i++) {
    107:     x0 = xx[4*i]; x1 = xx[4*i+1]; x2 = xx[4*i+2]; x3 = xx[4*i+3];

    109:     yy[4*i]   = diag[0]*x0 + diag[4]*x1 + diag[8]*x2  + diag[12]*x3;
    110:     yy[4*i+1] = diag[1]*x0 + diag[5]*x1 + diag[9]*x2  + diag[13]*x3;
    111:     yy[4*i+2] = diag[2]*x0 + diag[6]*x1 + diag[10]*x2 + diag[14]*x3;
    112:     yy[4*i+3] = diag[3]*x0 + diag[7]*x1 + diag[11]*x2 + diag[15]*x3;
    113:     diag     += 16;
    114:   }
    115:   VecRestoreArrayRead(x,&xx);
    116:   VecRestoreArray(y,&yy);
    117:   PetscLogFlops(28.0*m);
    118:   return(0);
    119: }
    122: static PetscErrorCode PCApply_PBJacobi_5(PC pc,Vec x,Vec y)
    123: {
    124:   PC_PBJacobi     *jac = (PC_PBJacobi*)pc->data;
    125:   PetscErrorCode  ierr;
    126:   PetscInt        i,m = jac->mbs;
    127:   const MatScalar *diag = jac->diag;
    128:   PetscScalar     x0,x1,x2,x3,x4,*yy;
    129:   const PetscScalar *xx;

    132:   VecGetArrayRead(x,&xx);
    133:   VecGetArray(y,&yy);
    134:   for (i=0; i<m; i++) {
    135:     x0 = xx[5*i]; x1 = xx[5*i+1]; x2 = xx[5*i+2]; x3 = xx[5*i+3]; x4 = xx[5*i+4];

    137:     yy[5*i]   = diag[0]*x0 + diag[5]*x1 + diag[10]*x2  + diag[15]*x3 + diag[20]*x4;
    138:     yy[5*i+1] = diag[1]*x0 + diag[6]*x1 + diag[11]*x2  + diag[16]*x3 + diag[21]*x4;
    139:     yy[5*i+2] = diag[2]*x0 + diag[7]*x1 + diag[12]*x2 + diag[17]*x3 + diag[22]*x4;
    140:     yy[5*i+3] = diag[3]*x0 + diag[8]*x1 + diag[13]*x2 + diag[18]*x3 + diag[23]*x4;
    141:     yy[5*i+4] = diag[4]*x0 + diag[9]*x1 + diag[14]*x2 + diag[19]*x3 + diag[24]*x4;
    142:     diag     += 25;
    143:   }
    144:   VecRestoreArrayRead(x,&xx);
    145:   VecRestoreArray(y,&yy);
    146:   PetscLogFlops(45.0*m);
    147:   return(0);
    148: }
    151: static PetscErrorCode PCApply_PBJacobi_6(PC pc,Vec x,Vec y)
    152: {
    153:   PC_PBJacobi     *jac = (PC_PBJacobi*)pc->data;
    154:   PetscErrorCode  ierr;
    155:   PetscInt        i,m = jac->mbs;
    156:   const MatScalar *diag = jac->diag;
    157:   PetscScalar     x0,x1,x2,x3,x4,x5,*yy;
    158:   const PetscScalar *xx;

    161:   VecGetArrayRead(x,&xx);
    162:   VecGetArray(y,&yy);
    163:   for (i=0; i<m; i++) {
    164:     x0 = xx[6*i]; x1 = xx[6*i+1]; x2 = xx[6*i+2]; x3 = xx[6*i+3]; x4 = xx[6*i+4]; x5 = xx[6*i+5];

    166:     yy[6*i]   = diag[0]*x0 + diag[6]*x1  + diag[12]*x2  + diag[18]*x3 + diag[24]*x4 + diag[30]*x5;
    167:     yy[6*i+1] = diag[1]*x0 + diag[7]*x1  + diag[13]*x2  + diag[19]*x3 + diag[25]*x4 + diag[31]*x5;
    168:     yy[6*i+2] = diag[2]*x0 + diag[8]*x1  + diag[14]*x2  + diag[20]*x3 + diag[26]*x4 + diag[32]*x5;
    169:     yy[6*i+3] = diag[3]*x0 + diag[9]*x1  + diag[15]*x2  + diag[21]*x3 + diag[27]*x4 + diag[33]*x5;
    170:     yy[6*i+4] = diag[4]*x0 + diag[10]*x1 + diag[16]*x2  + diag[22]*x3 + diag[28]*x4 + diag[34]*x5;
    171:     yy[6*i+5] = diag[5]*x0 + diag[11]*x1 + diag[17]*x2  + diag[23]*x3 + diag[29]*x4 + diag[35]*x5;
    172:     diag     += 36;
    173:   }
    174:   VecRestoreArrayRead(x,&xx);
    175:   VecRestoreArray(y,&yy);
    176:   PetscLogFlops(66.0*m);
    177:   return(0);
    178: }
    181: static PetscErrorCode PCApply_PBJacobi_7(PC pc,Vec x,Vec y)
    182: {
    183:   PC_PBJacobi     *jac = (PC_PBJacobi*)pc->data;
    184:   PetscErrorCode  ierr;
    185:   PetscInt        i,m = jac->mbs;
    186:   const MatScalar *diag = jac->diag;
    187:   PetscScalar     x0,x1,x2,x3,x4,x5,x6,*yy;
    188:   const PetscScalar *xx;

    191:   VecGetArrayRead(x,&xx);
    192:   VecGetArray(y,&yy);
    193:   for (i=0; i<m; i++) {
    194:     x0 = xx[7*i]; x1 = xx[7*i+1]; x2 = xx[7*i+2]; x3 = xx[7*i+3]; x4 = xx[7*i+4]; x5 = xx[7*i+5]; x6 = xx[7*i+6];

    196:     yy[7*i]   = diag[0]*x0 + diag[7]*x1  + diag[14]*x2  + diag[21]*x3 + diag[28]*x4 + diag[35]*x5 + diag[42]*x6;
    197:     yy[7*i+1] = diag[1]*x0 + diag[8]*x1  + diag[15]*x2  + diag[22]*x3 + diag[29]*x4 + diag[36]*x5 + diag[43]*x6;
    198:     yy[7*i+2] = diag[2]*x0 + diag[9]*x1  + diag[16]*x2  + diag[23]*x3 + diag[30]*x4 + diag[37]*x5 + diag[44]*x6;
    199:     yy[7*i+3] = diag[3]*x0 + diag[10]*x1 + diag[17]*x2  + diag[24]*x3 + diag[31]*x4 + diag[38]*x5 + diag[45]*x6;
    200:     yy[7*i+4] = diag[4]*x0 + diag[11]*x1 + diag[18]*x2  + diag[25]*x3 + diag[32]*x4 + diag[39]*x5 + diag[46]*x6;
    201:     yy[7*i+5] = diag[5]*x0 + diag[12]*x1 + diag[19]*x2  + diag[26]*x3 + diag[33]*x4 + diag[40]*x5 + diag[47]*x6;
    202:     yy[7*i+6] = diag[6]*x0 + diag[13]*x1 + diag[20]*x2  + diag[27]*x3 + diag[34]*x4 + diag[41]*x5 + diag[48]*x6;
    203:     diag     += 49;
    204:   }
    205:   VecRestoreArrayRead(x,&xx);
    206:   VecRestoreArray(y,&yy);
    207:   PetscLogFlops(80.0*m);
    208:   return(0);
    209: }
    210: /* -------------------------------------------------------------------------- */
    213: static PetscErrorCode PCSetUp_PBJacobi(PC pc)
    214: {
    215:   PC_PBJacobi    *jac = (PC_PBJacobi*)pc->data;
    217:   Mat            A = pc->pmat;

    220:   if (A->rmap->n != A->cmap->n) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_SUP,"Supported only for square matrices and square storage");

    222:   MatInvertBlockDiagonal(A,&jac->diag);
    223:   MatGetBlockSize(A,&jac->bs);
    224:   jac->mbs = A->rmap->n/jac->bs;
    225:   switch (jac->bs) {
    226:   case 1:
    227:     pc->ops->apply = PCApply_PBJacobi_1;
    228:     break;
    229:   case 2:
    230:     pc->ops->apply = PCApply_PBJacobi_2;
    231:     break;
    232:   case 3:
    233:     pc->ops->apply = PCApply_PBJacobi_3;
    234:     break;
    235:   case 4:
    236:     pc->ops->apply = PCApply_PBJacobi_4;
    237:     break;
    238:   case 5:
    239:     pc->ops->apply = PCApply_PBJacobi_5;
    240:     break;
    241:   case 6:
    242:     pc->ops->apply = PCApply_PBJacobi_6;
    243:     break;
    244:   case 7:
    245:     pc->ops->apply = PCApply_PBJacobi_7;
    246:     break;
    247:   default:
    248:     SETERRQ1(PetscObjectComm((PetscObject)pc),PETSC_ERR_SUP,"not supported for block size %D",jac->bs);
    249:   }
    250:   return(0);
    251: }
    252: /* -------------------------------------------------------------------------- */
    255: static PetscErrorCode PCDestroy_PBJacobi(PC pc)
    256: {

    260:   /*
    261:       Free the private data structure that was hanging off the PC
    262:   */
    263:   PetscFree(pc->data);
    264:   return(0);
    265: }

    269: static PetscErrorCode PCView_PBJacobi(PC pc,PetscViewer viewer)
    270: {
    272:   PC_PBJacobi    *jac = (PC_PBJacobi*)pc->data;
    273:   PetscBool      iascii;

    276:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&iascii);
    277:   if (iascii) {
    278:     PetscViewerASCIIPrintf(viewer,"  point-block Jacobi: block size %D\n",jac->bs);
    279:   }
    280:   return(0);
    281: }

    283: /* -------------------------------------------------------------------------- */
    284: /*MC
    285:      PCPBJACOBI - Point block Jacobi preconditioner

    288:    Notes: See PCJACOBI for point Jacobi preconditioning

    290:    This works for AIJ and BAIJ matrices and uses the blocksize provided to the matrix

    292:    Uses dense LU factorization with partial pivoting to invert the blocks; if a zero pivot
    293:    is detected a PETSc error is generated.

    295:    Developer Notes: This should support the PCSetErrorIfFailure() flag set to PETSC_TRUE to allow
    296:    the factorization to continue even after a zero pivot is found resulting in a Nan and hence
    297:    terminating KSP with a KSP_DIVERGED_NANORIF allowing
    298:    a nonlinear solver/ODE integrator to recover without stopping the program as currently happens.

    300:    Developer Note: Perhaps should provide an option that allows generation of a valid preconditioner
    301:    even if a block is singular as the PCJACOBI does.

    303:    Level: beginner

    305:   Concepts: point block Jacobi

    308: .seealso:  PCCreate(), PCSetType(), PCType (for list of available types), PC, PCJACOBI

    310: M*/

    314: PETSC_EXTERN PetscErrorCode PCCreate_PBJacobi(PC pc)
    315: {
    316:   PC_PBJacobi    *jac;

    320:   /*
    321:      Creates the private data structure for this preconditioner and
    322:      attach it to the PC object.
    323:   */
    324:   PetscNewLog(pc,&jac);
    325:   pc->data = (void*)jac;

    327:   /*
    328:      Initialize the pointers to vectors to ZERO; these will be used to store
    329:      diagonal entries of the matrix for fast preconditioner application.
    330:   */
    331:   jac->diag = 0;

    333:   /*
    334:       Set the pointers for the functions that are provided above.
    335:       Now when the user-level routines (such as PCApply(), PCDestroy(), etc.)
    336:       are called, they will automatically call these functions.  Note we
    337:       choose not to provide a couple of these functions since they are
    338:       not needed.
    339:   */
    340:   pc->ops->apply               = 0; /*set depending on the block size */
    341:   pc->ops->applytranspose      = 0;
    342:   pc->ops->setup               = PCSetUp_PBJacobi;
    343:   pc->ops->destroy             = PCDestroy_PBJacobi;
    344:   pc->ops->setfromoptions      = 0;
    345:   pc->ops->view                = PCView_PBJacobi;
    346:   pc->ops->applyrichardson     = 0;
    347:   pc->ops->applysymmetricleft  = 0;
    348:   pc->ops->applysymmetricright = 0;
    349:   return(0);
    350: }