Date: 2026-01-20T11:35:41+00:00

Actual source code: dvdinitv.c

      1: /*
      2:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      3:    SLEPc - Scalable Library for Eigenvalue Problem Computations
      4:    Copyright (c) 2002-, 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: initialize subspace V
     14: */

     16: #include "davidson.h"

     18: typedef struct {
     19:   PetscInt k;                 /* desired initial subspace size */
     20:   PetscInt user;              /* number of user initial vectors */
     21:   void     *old_initV_data;   /* old initV data */
     22: } dvdInitV;

     24: static PetscErrorCode dvd_initV_classic_0(dvdDashboard *d)
     25: {
     26:   dvdInitV       *data = (dvdInitV*)d->initV_data;
     27:   PetscInt       i,user = PetscMin(data->user,d->eps->mpd), l,k;

     29:   PetscFunctionBegin;
     30:   PetscCall(BVGetActiveColumns(d->eps->V,&l,&k));
     31:   /* User vectors are added at the beginning, so no active column should be in V */
     32:   PetscAssert(data->user==0 || l==0,PETSC_COMM_SELF,PETSC_ERR_PLIB,"Consistency broken");
     33:   /* Generate a set of random initial vectors and orthonormalize them */
     34:   for (i=l+user;i<l+data->k && i<d->eps->ncv && i-l<d->eps->mpd;i++) PetscCall(BVSetRandomColumn(d->eps->V,i));
     35:   d->V_tra_s = 0; d->V_tra_e = 0;
     36:   d->V_new_s = 0; d->V_new_e = i-l;

     38:   /* After that the user vectors will be destroyed */
     39:   data->user = 0;
     40:   PetscFunctionReturn(PETSC_SUCCESS);
     41: }

     43: static PetscErrorCode dvd_initV_krylov_0(dvdDashboard *d)
     44: {
     45:   dvdInitV       *data = (dvdInitV*)d->initV_data;
     46:   PetscInt       i,user = PetscMin(data->user,d->eps->mpd),l,k;
     47:   Vec            av,v1,v2;

     49:   PetscFunctionBegin;
     50:   PetscCall(BVGetActiveColumns(d->eps->V,&l,&k));
     51:   /* User vectors are added at the beginning, so no active column should be in V */
     52:   PetscAssert(data->user==0 || l==0,PETSC_COMM_SELF,PETSC_ERR_PLIB,"Consistency broken");

     54:   /* If needed, generate a random vector for starting the arnoldi method */
     55:   if (user == 0) {
     56:     PetscCall(BVSetRandomColumn(d->eps->V,l));
     57:     user = 1;
     58:   }

     60:   /* Perform k steps of Arnoldi with the operator K^{-1}*(t[1]*A-t[2]*B) */
     61:   PetscCall(dvd_orthV(d->eps->V,l,l+user));
     62:   for (i=l+user;i<l+data->k && i<d->eps->ncv && i-l<d->eps->mpd;i++) {
     63:     /* aux <- theta[1]A*in - theta[0]*B*in */
     64:     PetscCall(BVGetColumn(d->eps->V,i,&v1));
     65:     PetscCall(BVGetColumn(d->eps->V,i-user,&v2));
     66:     PetscCall(BVGetColumn(d->auxBV,0,&av));
     67:     if (d->B) {
     68:       PetscCall(MatMult(d->A,v2,v1));
     69:       PetscCall(MatMult(d->B,v2,av));
     70:       PetscCall(VecAXPBY(av,d->target[1],-d->target[0],v1));
     71:     } else {
     72:       PetscCall(MatMult(d->A,v2,av));
     73:       PetscCall(VecAXPBY(av,-d->target[0],d->target[1],v2));
     74:     }
     75:     PetscCall(d->improvex_precond(d,0,av,v1));
     76:     PetscCall(BVRestoreColumn(d->eps->V,i,&v1));
     77:     PetscCall(BVRestoreColumn(d->eps->V,i-user,&v2));
     78:     PetscCall(BVRestoreColumn(d->auxBV,0,&av));
     79:     PetscCall(dvd_orthV(d->eps->V,i,i+1));
     80:   }

     82:   d->V_tra_s = 0; d->V_tra_e = 0;
     83:   d->V_new_s = 0; d->V_new_e = i-l;

     85:   /* After that the user vectors will be destroyed */
     86:   data->user = 0;
     87:   PetscFunctionReturn(PETSC_SUCCESS);
     88: }

     90: static PetscErrorCode dvd_initV_d(dvdDashboard *d)
     91: {
     92:   dvdInitV       *data = (dvdInitV*)d->initV_data;

     94:   PetscFunctionBegin;
     95:   /* Restore changes in dvdDashboard */
     96:   d->initV_data = data->old_initV_data;

     98:   /* Free local data */
     99:   PetscCall(PetscFree(data));
    100:   PetscFunctionReturn(PETSC_SUCCESS);
    101: }

    103: PetscErrorCode dvd_initV(dvdDashboard *d, dvdBlackboard *b, PetscInt k,PetscInt user, PetscBool krylov)
    104: {
    105:   dvdInitV       *data;

    107:   PetscFunctionBegin;
    108:   /* Setting configuration constrains */
    109:   b->max_size_V = PetscMax(b->max_size_V, k);

    111:   /* Setup the step */
    112:   if (b->state >= DVD_STATE_CONF) {
    113:     PetscCall(PetscNew(&data));
    114:     data->k = k;
    115:     data->user = user;
    116:     data->old_initV_data = d->initV_data;
    117:     d->initV_data = data;
    118:     if (krylov) d->initV = dvd_initV_krylov_0;
    119:     else d->initV = dvd_initV_classic_0;
    120:     PetscCall(EPSDavidsonFLAdd(&d->destroyList,dvd_initV_d));
    121:   }
    122:   PetscFunctionReturn(PETSC_SUCCESS);
    123: }

    125: PetscErrorCode dvd_orthV(BV V,PetscInt V_new_s,PetscInt V_new_e)
    126: {
    127:   PetscInt       i;

    129:   PetscFunctionBegin;
    130:   for (i=V_new_s;i<V_new_e;i++) PetscCall(BVOrthonormalizeColumn(V,i,PETSC_TRUE,NULL,NULL));
    131:   PetscFunctionReturn(PETSC_SUCCESS);
    132: }