Actual source code: stshellmat.c
slepc-3.10.1 2018-10-23
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      1: /*
      2:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      3:    SLEPc - Scalable Library for Eigenvalue Problem Computations
      4:    Copyright (c) 2002-2018, Universitat Politecnica de Valencia, Spain

      6:    This file is part of SLEPc.
      7:    SLEPc is distributed under a 2-clause BSD license (see LICENSE).
      8:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      9: */
     10: /*
     11:    Subroutines that implement various operations of the matrix associated with
     12:    the shift-and-invert technique for eigenvalue problems
     13: */

     15: #include <slepc/private/stimpl.h>

     17: typedef struct {
     18:   PetscScalar alpha;
     19:   PetscScalar *coeffs;
     20:   ST          st;
     21:   Vec         z;
     22:   PetscInt    nmat;
     23:   PetscInt    *matIdx;
     24: } ST_SHELLMAT;

     26: PetscErrorCode STMatShellShift(Mat A,PetscScalar alpha)
     27: {
     29:   ST_SHELLMAT    *ctx;

     32:   MatShellGetContext(A,(void**)&ctx);
     33:   ctx->alpha = alpha;
     34:   return(0);
     35: }

     37: /*
     38:   For i=0:nmat-1 computes y = (sum_i (coeffs[i]*alpha^i*st->A[idx[i]]))x
     39:   If null coeffs computes with coeffs[i]=1.0
     40: */
     41: static PetscErrorCode MatMult_Shell(Mat A,Vec x,Vec y)
     42: {
     44:   ST_SHELLMAT    *ctx;
     45:   ST             st;
     46:   PetscInt       i;
     47:   PetscScalar    t=1.0,c;

     50:   MatShellGetContext(A,(void**)&ctx);
     51:   st = ctx->st;
     52:   MatMult(st->A[ctx->matIdx[0]],x,y);
     53:   if (ctx->coeffs && ctx->coeffs[0]!=1.0) {
     54:     VecScale(y,ctx->coeffs[0]);
     55:   }
     56:   if (ctx->alpha!=0.0) {
     57:     for (i=1;i<ctx->nmat;i++) {
     58:       MatMult(st->A[ctx->matIdx[i]],x,ctx->z);
     59:       t *= ctx->alpha;
     60:       c = (ctx->coeffs)?t*ctx->coeffs[i]:t;
     61:       VecAXPY(y,c,ctx->z);
     62:     }
     63:     if (ctx->nmat==1) {    /* y = (A + alpha*I) x */
     64:       VecAXPY(y,ctx->alpha,x);
     65:     }
     66:   }
     67:   return(0);
     68: }

     70: static PetscErrorCode MatMultTranspose_Shell(Mat A,Vec x,Vec y)
     71: {
     73:   ST_SHELLMAT    *ctx;
     74:   ST             st;
     75:   PetscInt       i;
     76:   PetscScalar    t=1.0,c;

     79:   MatShellGetContext(A,(void**)&ctx);
     80:   st = ctx->st;
     81:   MatMultTranspose(st->A[ctx->matIdx[0]],x,y);
     82:   if (ctx->coeffs && ctx->coeffs[0]!=1.0) {
     83:     VecScale(y,ctx->coeffs[0]);
     84:   }
     85:   if (ctx->alpha!=0.0) {
     86:     for (i=1;i<ctx->nmat;i++) {
     87:       MatMultTranspose(st->A[ctx->matIdx[i]],x,ctx->z);
     88:       t *= ctx->alpha;
     89:       c = (ctx->coeffs)?t*ctx->coeffs[i]:t;
     90:       VecAXPY(y,c,ctx->z);
     91:     }
     92:     if (ctx->nmat==1) {    /* y = (A + alpha*I) x */
     93:       VecAXPY(y,ctx->alpha,x);
     94:     }
     95:   }
     96:   return(0);
     97: }

     99: static PetscErrorCode MatGetDiagonal_Shell(Mat A,Vec diag)
    100: {
    102:   ST_SHELLMAT    *ctx;
    103:   ST             st;
    104:   Vec            diagb;
    105:   PetscInt       i;
    106:   PetscScalar    t=1.0,c;

    109:   MatShellGetContext(A,(void**)&ctx);
    110:   st = ctx->st;
    111:   MatGetDiagonal(st->A[ctx->matIdx[0]],diag);
    112:   if (ctx->coeffs && ctx->coeffs[0]!=1.0) {
    113:     VecScale(diag,ctx->coeffs[0]);
    114:   }
    115:   if (ctx->alpha!=0.0) {
    116:     if (ctx->nmat==1) {    /* y = (A + alpha*I) x */
    117:       VecShift(diag,ctx->alpha);
    118:     } else {
    119:       VecDuplicate(diag,&diagb);
    120:       for (i=1;i<ctx->nmat;i++) {
    121:         MatGetDiagonal(st->A[ctx->matIdx[i]],diagb);
    122:         t *= ctx->alpha;
    123:         c = (ctx->coeffs)?t*ctx->coeffs[i]:t;
    124:         VecAYPX(diag,c,diagb);
    125:       }
    126:       VecDestroy(&diagb);
    127:     }
    128:   }
    129:   return(0);
    130: }

    132: static PetscErrorCode MatDestroy_Shell(Mat A)
    133: {
    135:   ST_SHELLMAT    *ctx;

    138:   MatShellGetContext(A,(void**)&ctx);
    139:   VecDestroy(&ctx->z);
    140:   PetscFree(ctx->matIdx);
    141:   PetscFree(ctx->coeffs);
    142:   PetscFree(ctx);
    143:   return(0);
    144: }

    146: PetscErrorCode STMatShellCreate(ST st,PetscScalar alpha,PetscInt nmat,PetscInt *matIdx,PetscScalar *coeffs,Mat *mat)
    147: {
    149:   PetscInt       n,m,N,M,i;
    150:   PetscBool      has=PETSC_FALSE,hasA,hasB;
    151:   ST_SHELLMAT    *ctx;

    154:   MatGetSize(st->A[0],&M,&N);
    155:   MatGetLocalSize(st->A[0],&m,&n);
    156:   PetscNew(&ctx);
    157:   ctx->st = st;
    158:   ctx->alpha = alpha;
    159:   ctx->nmat = matIdx?nmat:st->nmat;
    160:   PetscMalloc1(ctx->nmat,&ctx->matIdx);
    161:   if (matIdx) {
    162:     for (i=0;i<ctx->nmat;i++) ctx->matIdx[i] = matIdx[i];
    163:   } else {
    164:     ctx->matIdx[0] = 0;
    165:     if (ctx->nmat>1) ctx->matIdx[1] = 1;
    166:   }
    167:   if (coeffs) {
    168:     PetscMalloc1(ctx->nmat,&ctx->coeffs);
    169:     for (i=0;i<ctx->nmat;i++) ctx->coeffs[i] = coeffs[i];
    170:   }
    171:   MatCreateVecs(st->A[0],&ctx->z,NULL);
    172:   MatCreateShell(PetscObjectComm((PetscObject)st),m,n,M,N,(void*)ctx,mat);
    173:   MatShellSetOperation(*mat,MATOP_MULT,(void(*)(void))MatMult_Shell);
    174:   MatShellSetOperation(*mat,MATOP_MULT_TRANSPOSE,(void(*)(void))MatMultTranspose_Shell);
    175:   MatShellSetOperation(*mat,MATOP_DESTROY,(void(*)(void))MatDestroy_Shell);

    177:   MatHasOperation(st->A[ctx->matIdx[0]],MATOP_GET_DIAGONAL,&hasA);
    178:   if (st->nmat>1) {
    179:     has = hasA;
    180:     for (i=1;i<ctx->nmat;i++) {
    181:       MatHasOperation(st->A[ctx->matIdx[i]],MATOP_GET_DIAGONAL,&hasB);
    182:       has = (has && hasB)? PETSC_TRUE: PETSC_FALSE;
    183:     }
    184:   }
    185:   if ((hasA && st->nmat==1) || has) {
    186:     MatShellSetOperation(*mat,MATOP_GET_DIAGONAL,(void(*)(void))MatGetDiagonal_Shell);
    187:   }
    188:   return(0);
    189: }