Date: 2017-05-17T08:25:59+00:00

Actual source code: dvdgd2.c
slepc-3.7.4 2017-05-17
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      1: /*
      2:   SLEPc eigensolver: "davidson"

      4:   Step: improve the eigenvectors X with GD2

      6:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      7:    SLEPc - Scalable Library for Eigenvalue Problem Computations
      8:    Copyright (c) 2002-2016, Universitat Politecnica de Valencia, Spain

     10:    This file is part of SLEPc.

     12:    SLEPc is free software: you can redistribute it and/or modify it under  the
     13:    terms of version 3 of the GNU Lesser General Public License as published by
     14:    the Free Software Foundation.

     16:    SLEPc  is  distributed in the hope that it will be useful, but WITHOUT  ANY
     17:    WARRANTY;  without even the implied warranty of MERCHANTABILITY or  FITNESS
     18:    FOR  A  PARTICULAR PURPOSE. See the GNU Lesser General Public  License  for
     19:    more details.

     21:    You  should have received a copy of the GNU Lesser General  Public  License
     22:    along with SLEPc. If not, see <http://www.gnu.org/licenses/>.
     23:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     24: */

     26:  #include davidson.h

     28: typedef struct {
     29:   PetscInt size_X;
     30: } dvdImprovex_gd2;

     34: static PetscErrorCode dvd_improvex_gd2_d(dvdDashboard *d)
     35: {
     36:   PetscErrorCode  ierr;
     37:   dvdImprovex_gd2 *data = (dvdImprovex_gd2*)d->improveX_data;

     40:   /* Free local data and objects */
     41:   PetscFree(data);
     42:   return(0);
     43: }

     47: static PetscErrorCode dvd_improvex_gd2_gen(dvdDashboard *d,PetscInt r_s,PetscInt r_e,PetscInt *size_D)
     48: {
     49:   dvdImprovex_gd2 *data = (dvdImprovex_gd2*)d->improveX_data;
     50:   PetscErrorCode  ierr;
     51:   PetscInt        i,j,n,s,ld,k,lv,kv,max_size_D;
     52:   PetscScalar     *pX,*b;
     53:   Vec             *Ax,*Bx,v,*x;
     54:   Mat             M;
     55:   BV              X;

     58:   /* Compute the number of pairs to improve */
     59:   BVGetActiveColumns(d->eps->V,&lv,&kv);
     60:   max_size_D = d->eps->ncv-kv;
     61:   n = PetscMin(PetscMin(data->size_X*2,max_size_D),(r_e-r_s)*2)/2;
     62: #if !defined(PETSC_USE_COMPLEX)
     63:   /* If the last eigenvalue is a complex conjugate pair, n is increased by one */
     64:   for (i=0; i<n; i++) {
     65:     if (d->eigi[i] != 0.0) i++;
     66:   }
     67:   if (i > n) {
     68:     n = PetscMin(PetscMin(data->size_X*2,max_size_D),(n+1)*2)/2;
     69:     if (i > n) n--;
     70:   }
     71: #endif

     73:   /* Quick exit */
     74:   if (max_size_D == 0 || r_e-r_s <= 0 || n == 0) {
     75:    *size_D = 0;
     76:     return(0);
     77:   }

     79:   BVDuplicateResize(d->eps->V,4,&X);
     80:   MatCreateSeqDense(PETSC_COMM_SELF,4,2,NULL,&M);

     82:   /* Compute the eigenvectors of the selected pairs */
     83:   for (i=0;i<n;) {
     84:     k = r_s+i;
     85:     DSVectors(d->eps->ds,DS_MAT_X,&k,NULL);
     86:     i = k+1; /* skip complex conjugate pairs */
     87:   }
     88:   DSGetArray(d->eps->ds,DS_MAT_X,&pX);
     89:   DSGetLeadingDimension(d->eps->ds,&ld);

     91:   SlepcVecPoolGetVecs(d->auxV,n,&Ax);
     92:   SlepcVecPoolGetVecs(d->auxV,n,&Bx);

     94:   /* Bx <- B*X(i) */
     95:   if (d->BX) {
     96:     /* Compute the norms of the eigenvectors */
     97:     if (d->correctXnorm) {
     98:       dvd_improvex_compute_X(d,r_s,r_s+n,Bx,pX,ld);
     99:     } else {
    100:       for (i=0;i<n;i++) d->nX[r_s+i] = 1.0;
    101:     }
    102:     for (i=0;i<n;i++) {
    103:       BVMultVec(d->BX,1.0,0.0,Bx[i],&pX[ld*(r_s+i)]);
    104:     }
    105:   } else if (d->B) {
    106:     SlepcVecPoolGetVecs(d->auxV,1,&x);
    107:     for (i=0;i<n;i++) {
    108:       /* auxV(0) <- X(i) */
    109:       dvd_improvex_compute_X(d,r_s+i,r_s+i+1,x,pX,ld);
    110:       /* Bx(i) <- B*auxV(0) */
    111:       MatMult(d->B,x[0],Bx[i]);
    112:     }
    113:     SlepcVecPoolRestoreVecs(d->auxV,1,&x);
    114:   } else {
    115:     /* Bx <- X */
    116:     dvd_improvex_compute_X(d,r_s,r_s+n,Bx,pX,ld);
    117:   }

    119:   /* Ax <- A*X(i) */
    120:   for (i=0;i<n;i++) {
    121:     BVMultVec(d->AX,1.0,0.0,Ax[i],&pX[ld*(i+r_s)]);
    122:   }

    124:   DSRestoreArray(d->eps->ds,DS_MAT_X,&pX);

    126:   for (i=0,s=0;i<n;i+=s) {
    127: #if !defined(PETSC_USE_COMPLEX)
    128:     if (d->eigi[r_s+i] != 0.0) {
    129:        /* [Ax_i Ax_i+1 Bx_i Bx_i+1]*= [   1        0
    130:                                           0        1
    131:                                        -eigr_i -eigi_i
    132:                                         eigi_i -eigr_i] */
    133:       MatDenseGetArray(M,&b);
    134:       b[0] = b[5] = 1.0/d->nX[r_s+i];
    135:       b[2] = b[7] = -d->eigr[r_s+i]/d->nX[r_s+i];
    136:       b[6] = -(b[3] = d->eigi[r_s+i]/d->nX[r_s+i]);
    137:       b[1] = b[4] = 0.0;
    138:       MatDenseRestoreArray(M,&b);
    139:       BVInsertVec(X,0,Ax[i]);
    140:       BVInsertVec(X,1,Ax[i+1]);
    141:       BVInsertVec(X,2,Bx[i]);
    142:       BVInsertVec(X,3,Bx[i+1]);
    143:       BVSetActiveColumns(X,0,4);
    144:       BVMultInPlace(X,M,0,2);
    145:       BVCopyVec(X,0,Ax[i]);
    146:       BVCopyVec(X,1,Ax[i+1]);
    147:       s = 2;
    148:     } else
    149: #endif
    150:     {
    151:       /* [Ax_i Bx_i]*= [ 1/nX_i    conj(eig_i/nX_i)
    152:                        -eig_i/nX_i     1/nX_i       ] */
    153:       MatDenseGetArray(M,&b);
    154:       b[0] = 1.0/d->nX[r_s+i];
    155:       b[1] = -d->eigr[r_s+i]/d->nX[r_s+i];
    156:       b[4] = PetscConj(d->eigr[r_s+i]/d->nX[r_s+i]);
    157:       b[5] = 1.0/d->nX[r_s+i];
    158:       MatDenseRestoreArray(M,&b);
    159:       BVInsertVec(X,0,Ax[i]);
    160:       BVInsertVec(X,1,Bx[i]);
    161:       BVSetActiveColumns(X,0,2);
    162:       BVMultInPlace(X,M,0,2);
    163:       BVCopyVec(X,0,Ax[i]);
    164:       BVCopyVec(X,1,Bx[i]);
    165:       s = 1;
    166:     }
    167:     for (j=0;j<s;j++) d->nX[r_s+i+j] = 1.0;

    169:     /* Ax = R <- P*(Ax - eig_i*Bx) */
    170:     d->calcpairs_proj_res(d,r_s+i,r_s+i+s,&Ax[i]);

    172:     /* Check if the first eigenpairs are converged */
    173:     if (i == 0) {
    174:       d->preTestConv(d,0,s,s,&d->npreconv);
    175:       if (d->npreconv > 0) break;
    176:     }
    177:   }

    179:   /* D <- K*[Ax Bx] */
    180:   if (d->npreconv == 0) {
    181:     for (i=0;i<n;i++) {
    182:       BVGetColumn(d->eps->V,kv+i,&v);
    183:       d->improvex_precond(d,r_s+i,Ax[i],v);
    184:       BVRestoreColumn(d->eps->V,kv+i,&v);
    185:     }
    186:     for (i=n;i<n*2;i++) {
    187:       BVGetColumn(d->eps->V,kv+i,&v);
    188:       d->improvex_precond(d,r_s+i-n,Bx[i-n],v);
    189:       BVRestoreColumn(d->eps->V,kv+i,&v);
    190:     }
    191:     *size_D = 2*n;
    192: #if !defined(PETSC_USE_COMPLEX)
    193:     if (d->eigi[r_s] != 0.0) {
    194:       s = 4;
    195:     } else
    196: #endif
    197:     {
    198:       s = 2;
    199:     }
    200:     /* Prevent that short vectors are discarded in the orthogonalization */
    201:     for (i=0; i<s && i<*size_D; i++) {
    202:       if (d->eps->errest[d->nconv+r_s+i] > PETSC_MACHINE_EPSILON && d->eps->errest[d->nconv+r_s+i] < PETSC_MAX_REAL) {
    203:         BVScaleColumn(d->eps->V,i+kv,1.0/d->eps->errest[d->nconv+r_s+i]);
    204:       }
    205:     }
    206:   } else *size_D = 0;

    208:   SlepcVecPoolRestoreVecs(d->auxV,n,&Bx);
    209:   SlepcVecPoolRestoreVecs(d->auxV,n,&Ax);
    210:   BVDestroy(&X);
    211:   MatDestroy(&M);
    212:   return(0);
    213: }

    217: PetscErrorCode dvd_improvex_gd2(dvdDashboard *d,dvdBlackboard *b,KSP ksp,PetscInt max_bs)
    218: {
    219:   PetscErrorCode  ierr;
    220:   dvdImprovex_gd2 *data;
    221:   PC              pc;

    224:   /* Setting configuration constrains */
    225:   /* If the arithmetic is real and the problem is not Hermitian, then
    226:      the block size is incremented in one */
    227: #if !defined(PETSC_USE_COMPLEX)
    228:   if (!DVD_IS(d->sEP, DVD_EP_HERMITIAN)) {
    229:     max_bs++;
    230:     b->max_size_P = PetscMax(b->max_size_P,2);
    231:   } else
    232: #endif
    233:   {
    234:     b->max_size_P = PetscMax(b->max_size_P,1);
    235:   }
    236:   b->max_size_X = PetscMax(b->max_size_X,max_bs);

    238:   /* Setup the preconditioner */
    239:   if (ksp) {
    240:     KSPGetPC(ksp,&pc);
    241:     dvd_static_precond_PC(d,b,pc);
    242:   } else {
    243:     dvd_static_precond_PC(d,b,0);
    244:   }

    246:   /* Setup the step */
    247:   if (b->state >= DVD_STATE_CONF) {
    248:     PetscNewLog(d->eps,&data);
    249:     d->improveX_data = data;
    250:     data->size_X = b->max_size_X;
    251:     d->improveX = dvd_improvex_gd2_gen;

    253:     EPSDavidsonFLAdd(&d->destroyList,dvd_improvex_gd2_d);
    254:   }
    255:   return(0);
    256: }