Actual source code: ks-indef.c

slepc-3.7.4 2017-05-17
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  1: /*

  3:    SLEPc eigensolver: "krylovschur"

  5:    Method: Krylov-Schur for symmetric-indefinite eigenproblems

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

 11:    This file is part of SLEPc.

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

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

 22:    You  should have received a copy of the GNU Lesser General  Public  License
 23:    along with SLEPc. If not, see <http://www.gnu.org/licenses/>.
 24:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 25: */
 26: #include <slepc/private/epsimpl.h>
 27:  #include krylovschur.h

 31: PetscErrorCode EPSSolve_KrylovSchur_Indefinite(EPS eps)
 32: {
 33:   PetscErrorCode  ierr;
 34:   EPS_KRYLOVSCHUR *ctx = (EPS_KRYLOVSCHUR*)eps->data;
 35:   PetscInt        i,k,l,ld,nv,t,nconv=0;
 36:   Mat             U;
 37:   Vec             vomega,w=eps->work[0];
 38:   PetscScalar     *Q,*aux;
 39:   PetscReal       *a,*b,*r,beta,beta1=1.0,*omega;
 40:   PetscBool       breakdown=PETSC_FALSE,symmlost=PETSC_FALSE;

 43:   DSGetLeadingDimension(eps->ds,&ld);

 45:   /* Get the starting Lanczos vector */
 46:   EPSGetStartVector(eps,0,NULL);

 48:   /* Extract sigma[0] from BV, computed during normalization */
 49:   BVSetActiveColumns(eps->V,0,1);
 50:   VecCreateSeq(PETSC_COMM_SELF,1,&vomega);
 51:   BVGetSignature(eps->V,vomega);
 52:   VecGetArray(vomega,&aux);
 53:   DSGetArrayReal(eps->ds,DS_MAT_D,&omega);
 54:   omega[0] = PetscRealPart(aux[0]);
 55:   DSRestoreArrayReal(eps->ds,DS_MAT_D,&omega);
 56:   VecRestoreArray(vomega,&aux);
 57:   VecDestroy(&vomega);
 58:   l = 0;

 60:   /* Restart loop */
 61:   while (eps->reason == EPS_CONVERGED_ITERATING) {
 62:     eps->its++;

 64:     /* Compute an nv-step Lanczos factorization */
 65:     nv = PetscMin(eps->nconv+eps->mpd,eps->ncv);
 66:     DSGetArrayReal(eps->ds,DS_MAT_T,&a);
 67:     b = a + ld;
 68:     DSGetArrayReal(eps->ds,DS_MAT_D,&omega);
 69:     EPSPseudoLanczos(eps,a,b,omega,eps->nconv+l,&nv,&breakdown,&symmlost,NULL,w);
 70:     if (symmlost) {
 71:       eps->reason = EPS_DIVERGED_SYMMETRY_LOST;
 72:       if (nv==eps->nconv+l+1) { eps->nconv = nconv; break; }
 73:     }
 74:     beta = b[nv-1];
 75:     DSRestoreArrayReal(eps->ds,DS_MAT_T,&a);
 76:     DSRestoreArrayReal(eps->ds,DS_MAT_D,&omega);
 77:     DSSetDimensions(eps->ds,nv,0,eps->nconv,eps->nconv+l);
 78:     if (l==0) {
 79:       DSSetState(eps->ds,DS_STATE_INTERMEDIATE);
 80:     } else {
 81:       DSSetState(eps->ds,DS_STATE_RAW);
 82:     }
 83:     BVSetActiveColumns(eps->V,eps->nconv,nv);

 85:     /* Solve projected problem */
 86:     DSSolve(eps->ds,eps->eigr,eps->eigi);
 87:     DSSort(eps->ds,eps->eigr,eps->eigi,NULL,NULL,NULL);

 89:     /* Check convergence */
 90:     DSGetDimensions(eps->ds,NULL,NULL,NULL,NULL,&t);
 91: #if 0
 92:     /* take into account also left residual */
 93:     BVGetColumn(eps->V,nv,&u);
 94:     VecNorm(u,NORM_2,&beta1);
 95:     BVRestoreColumn(eps->V,nv,&u);
 96:     VecNorm(w,NORM_2,&beta2);  /* w contains B*V[nv] */
 97:     beta1 = PetscMax(beta1,beta2);
 98: #endif
 99:     EPSKrylovConvergence(eps,PETSC_FALSE,eps->nconv,t-eps->nconv,beta*beta1,1.0,&k);
100:     (*eps->stopping)(eps,eps->its,eps->max_it,k,eps->nev,&eps->reason,eps->stoppingctx);
101:     nconv = k;

103:     /* Update l */
104:     if (eps->reason != EPS_CONVERGED_ITERATING || breakdown) l = 0;
105:     else {
106:       l = PetscMax(1,(PetscInt)((nv-k)*ctx->keep));
107:       l = PetscMin(l,t);
108:       DSGetArrayReal(eps->ds,DS_MAT_T,&a);
109:       if (*(a+ld+k+l-1)!=0) {
110:         if (k+l<t-1) l = l+1;
111:         else l = l-1;
112:       }
113:       DSRestoreArrayReal(eps->ds,DS_MAT_T,&a);
114:     }
115:     if (!ctx->lock && l>0) { l += k; k = 0; } /* non-locking variant: reset no. of converged pairs */

117:     if (eps->reason == EPS_CONVERGED_ITERATING) {
118:       if (breakdown) {
119:         SETERRQ1(PetscObjectComm((PetscObject)eps),PETSC_ERR_CONV_FAILED,"Breakdown in Indefinite Krylov-Schur (beta=%g)",beta);
120:       } else {
121:         /* Prepare the Rayleigh quotient for restart */
122:         DSGetArray(eps->ds,DS_MAT_Q,&Q);
123:         DSGetArrayReal(eps->ds,DS_MAT_T,&a);
124:         DSGetArrayReal(eps->ds,DS_MAT_D,&omega);
125:         b = a + ld;
126:         r = a + 2*ld;
127:         for (i=k;i<k+l;i++) {
128:           r[i] = PetscRealPart(Q[nv-1+i*ld]*beta);
129:         }
130:         b[k+l-1] = r[k+l-1];
131:         omega[k+l] = omega[nv];
132:         DSRestoreArrayReal(eps->ds,DS_MAT_T,&a);
133:         DSRestoreArray(eps->ds,DS_MAT_Q,&Q);
134:         DSRestoreArrayReal(eps->ds,DS_MAT_D,&omega);
135:       }
136:     }
137:     /* Update the corresponding vectors V(:,idx) = V*Q(:,idx) */
138:     DSGetMat(eps->ds,DS_MAT_Q,&U);
139:     BVMultInPlace(eps->V,U,eps->nconv,k+l);
140:     MatDestroy(&U);

142:     /* Move restart vector and update signature */
143:     if (eps->reason == EPS_CONVERGED_ITERATING && !breakdown) {
144:       BVCopyColumn(eps->V,nv,k+l);
145:       DSGetArrayReal(eps->ds,DS_MAT_D,&omega);
146:       VecCreateSeq(PETSC_COMM_SELF,k+l,&vomega);
147:       VecGetArray(vomega,&aux);
148:       for (i=0;i<k+l;i++) aux[i] = omega[i];
149:       VecRestoreArray(vomega,&aux);
150:       BVSetActiveColumns(eps->V,0,k+l);
151:       BVSetSignature(eps->V,vomega);
152:       VecDestroy(&vomega);
153:       DSRestoreArrayReal(eps->ds,DS_MAT_D,&omega);
154:     }

156:     eps->nconv = k;
157:     EPSMonitor(eps,eps->its,nconv,eps->eigr,eps->eigi,eps->errest,nv);
158:   }
159:   DSSetDimensions(eps->ds,eps->nconv,0,0,0);
160:   DSSetState(eps->ds,DS_STATE_RAW);
161:   return(0);
162: }