Actual source code: dvdgd2.c

slepc-3.11.2 2019-07-30
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  1: /*
  2:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
  3:    SLEPc - Scalable Library for Eigenvalue Problem Computations
  4:    Copyright (c) 2002-2019, 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:    SLEPc eigensolver: "davidson"

 13:    Step: improve the eigenvectors X with GD2
 14: */

 16: #include "davidson.h"

 18: typedef struct {
 19:   PetscInt size_X;
 20: } dvdImprovex_gd2;

 22: static PetscErrorCode dvd_improvex_gd2_d(dvdDashboard *d)
 23: {
 24:   PetscErrorCode  ierr;
 25:   dvdImprovex_gd2 *data = (dvdImprovex_gd2*)d->improveX_data;

 28:   /* Free local data and objects */
 29:   PetscFree(data);
 30:   return(0);
 31: }

 33: static PetscErrorCode dvd_improvex_gd2_gen(dvdDashboard *d,PetscInt r_s,PetscInt r_e,PetscInt *size_D)
 34: {
 35:   dvdImprovex_gd2 *data = (dvdImprovex_gd2*)d->improveX_data;
 36:   PetscErrorCode  ierr;
 37:   PetscInt        i,j,n,s,ld,lv,kv,max_size_D;
 38:   PetscInt        oldnpreconv = d->npreconv;
 39:   PetscScalar     *pX,*b;
 40:   Vec             *Ax,*Bx,v,*x;
 41:   Mat             M;
 42:   BV              X;

 45:   /* Compute the number of pairs to improve */
 46:   BVGetActiveColumns(d->eps->V,&lv,&kv);
 47:   max_size_D = d->eps->ncv-kv;
 48:   n = PetscMin(PetscMin(data->size_X*2,max_size_D),(r_e-r_s)*2)/2;

 50:   /* Quick exit */
 51:   if (max_size_D == 0 || r_e-r_s <= 0 || n == 0) {
 52:    *size_D = 0;
 53:     return(0);
 54:   }

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

 59:   /* Compute the eigenvectors of the selected pairs */
 60:   for (i=r_s;i<r_s+n; i++) {
 61:     DSVectors(d->eps->ds,DS_MAT_X,&i,NULL);
 62:   }
 63:   DSGetArray(d->eps->ds,DS_MAT_X,&pX);
 64:   DSGetLeadingDimension(d->eps->ds,&ld);

 66:   SlepcVecPoolGetVecs(d->auxV,n,&Ax);
 67:   SlepcVecPoolGetVecs(d->auxV,n,&Bx);

 69:   /* Bx <- B*X(i) */
 70:   if (d->BX) {
 71:     /* Compute the norms of the eigenvectors */
 72:     if (d->correctXnorm) {
 73:       dvd_improvex_compute_X(d,r_s,r_s+n,Bx,pX,ld);
 74:     } else {
 75:       for (i=0;i<n;i++) d->nX[r_s+i] = 1.0;
 76:     }
 77:     for (i=0;i<n;i++) {
 78:       BVMultVec(d->BX,1.0,0.0,Bx[i],&pX[ld*(r_s+i)]);
 79:     }
 80:   } else if (d->B) {
 81:     SlepcVecPoolGetVecs(d->auxV,1,&x);
 82:     for (i=0;i<n;i++) {
 83:       /* auxV(0) <- X(i) */
 84:       dvd_improvex_compute_X(d,r_s+i,r_s+i+1,x,pX,ld);
 85:       /* Bx(i) <- B*auxV(0) */
 86:       MatMult(d->B,x[0],Bx[i]);
 87:     }
 88:     SlepcVecPoolRestoreVecs(d->auxV,1,&x);
 89:   } else {
 90:     /* Bx <- X */
 91:     dvd_improvex_compute_X(d,r_s,r_s+n,Bx,pX,ld);
 92:   }

 94:   /* Ax <- A*X(i) */
 95:   for (i=0;i<n;i++) {
 96:     BVMultVec(d->AX,1.0,0.0,Ax[i],&pX[ld*(i+r_s)]);
 97:   }

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

101:   for (i=0,s=0;i<n;i+=s) {
102: #if !defined(PETSC_USE_COMPLEX)
103:     if (d->eigi[r_s+i] != 0.0 && i+2<=n) {
104:        /* [Ax_i Ax_i+1 Bx_i Bx_i+1]*= [   1        0
105:                                           0        1
106:                                        -eigr_i -eigi_i
107:                                         eigi_i -eigr_i] */
108:       MatDenseGetArray(M,&b);
109:       b[0] = b[5] = 1.0/d->nX[r_s+i];
110:       b[2] = b[7] = -d->eigr[r_s+i]/d->nX[r_s+i];
111:       b[6] = -(b[3] = d->eigi[r_s+i]/d->nX[r_s+i]);
112:       b[1] = b[4] = 0.0;
113:       MatDenseRestoreArray(M,&b);
114:       BVInsertVec(X,0,Ax[i]);
115:       BVInsertVec(X,1,Ax[i+1]);
116:       BVInsertVec(X,2,Bx[i]);
117:       BVInsertVec(X,3,Bx[i+1]);
118:       BVSetActiveColumns(X,0,4);
119:       BVMultInPlace(X,M,0,2);
120:       BVCopyVec(X,0,Ax[i]);
121:       BVCopyVec(X,1,Ax[i+1]);
122:       s = 2;
123:     } else
124: #endif
125:     {
126:       /* [Ax_i Bx_i]*= [ 1/nX_i    conj(eig_i/nX_i)
127:                        -eig_i/nX_i     1/nX_i       ] */
128:       MatDenseGetArray(M,&b);
129:       b[0] = 1.0/d->nX[r_s+i];
130:       b[1] = -d->eigr[r_s+i]/d->nX[r_s+i];
131:       b[4] = PetscConj(d->eigr[r_s+i]/d->nX[r_s+i]);
132:       b[5] = 1.0/d->nX[r_s+i];
133:       MatDenseRestoreArray(M,&b);
134:       BVInsertVec(X,0,Ax[i]);
135:       BVInsertVec(X,1,Bx[i]);
136:       BVSetActiveColumns(X,0,2);
137:       BVMultInPlace(X,M,0,2);
138:       BVCopyVec(X,0,Ax[i]);
139:       BVCopyVec(X,1,Bx[i]);
140:       s = 1;
141:     }
142:     for (j=0;j<s;j++) d->nX[r_s+i+j] = 1.0;

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

147:     /* Check if the first eigenpairs are converged */
148:     if (i == 0) {
149:       d->preTestConv(d,0,r_s+s,r_s+s,&d->npreconv);
150:       if (d->npreconv > oldnpreconv) break;
151:     }
152:   }

154:   /* D <- K*[Ax Bx] */
155:   if (d->npreconv <= oldnpreconv) {
156:     for (i=0;i<n;i++) {
157:       BVGetColumn(d->eps->V,kv+i,&v);
158:       d->improvex_precond(d,r_s+i,Ax[i],v);
159:       BVRestoreColumn(d->eps->V,kv+i,&v);
160:     }
161:     for (i=n;i<n*2;i++) {
162:       BVGetColumn(d->eps->V,kv+i,&v);
163:       d->improvex_precond(d,r_s+i-n,Bx[i-n],v);
164:       BVRestoreColumn(d->eps->V,kv+i,&v);
165:     }
166:     *size_D = 2*n;
167: #if !defined(PETSC_USE_COMPLEX)
168:     if (d->eigi[r_s] != 0.0) {
169:       s = 4;
170:     } else
171: #endif
172:     {
173:       s = 2;
174:     }
175:     /* Prevent that short vectors are discarded in the orthogonalization */
176:     for (i=0; i<s && i<*size_D; i++) {
177:       if (d->eps->errest[d->nconv+r_s+i] > PETSC_MACHINE_EPSILON && d->eps->errest[d->nconv+r_s+i] < PETSC_MAX_REAL) {
178:         BVScaleColumn(d->eps->V,i+kv,1.0/d->eps->errest[d->nconv+r_s+i]);
179:       }
180:     }
181:   } else *size_D = 0;

183:   SlepcVecPoolRestoreVecs(d->auxV,n,&Bx);
184:   SlepcVecPoolRestoreVecs(d->auxV,n,&Ax);
185:   BVDestroy(&X);
186:   MatDestroy(&M);
187:   return(0);
188: }

190: PetscErrorCode dvd_improvex_gd2(dvdDashboard *d,dvdBlackboard *b,KSP ksp,PetscInt max_bs)
191: {
192:   PetscErrorCode  ierr;
193:   dvdImprovex_gd2 *data;
194:   PC              pc;

197:   /* Setting configuration constrains */
198:   /* If the arithmetic is real and the problem is not Hermitian, then
199:      the block size is incremented in one */
200: #if !defined(PETSC_USE_COMPLEX)
201:   if (!DVD_IS(d->sEP, DVD_EP_HERMITIAN)) {
202:     max_bs++;
203:     b->max_size_P = PetscMax(b->max_size_P,2);
204:   } else
205: #endif
206:   {
207:     b->max_size_P = PetscMax(b->max_size_P,1);
208:   }
209:   b->max_size_X = PetscMax(b->max_size_X,max_bs);

211:   /* Setup the preconditioner */
212:   if (ksp) {
213:     KSPGetPC(ksp,&pc);
214:     dvd_static_precond_PC(d,b,pc);
215:   } else {
216:     dvd_static_precond_PC(d,b,0);
217:   }

219:   /* Setup the step */
220:   if (b->state >= DVD_STATE_CONF) {
221:     PetscNewLog(d->eps,&data);
222:     d->improveX_data = data;
223:     data->size_X = b->max_size_X;
224:     d->improveX = dvd_improvex_gd2_gen;

226:     EPSDavidsonFLAdd(&d->destroyList,dvd_improvex_gd2_d);
227:   }
228:   return(0);
229: }