Actual source code: nepdefault.c

slepc-3.18.2 2023-01-26
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  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:    Simple default routines for common NEP operations
 12: */

 14: #include <slepc/private/nepimpl.h>

 16: /*@
 17:    NEPSetWorkVecs - Sets a number of work vectors into a NEP object

 19:    Collective on nep

 21:    Input Parameters:
 22: +  nep - nonlinear eigensolver context
 23: -  nw  - number of work vectors to allocate

 25:    Developer Notes:
 26:    This is SLEPC_EXTERN because it may be required by user plugin NEP
 27:    implementations.

 29:    Level: developer

 31: .seealso: NEPSetUp()
 32: @*/
 33: PetscErrorCode NEPSetWorkVecs(NEP nep,PetscInt nw)
 34: {
 35:   Vec            t;

 40:   if (nep->nwork < nw) {
 41:     VecDestroyVecs(nep->nwork,&nep->work);
 42:     nep->nwork = nw;
 43:     BVGetColumn(nep->V,0,&t);
 44:     VecDuplicateVecs(t,nw,&nep->work);
 45:     BVRestoreColumn(nep->V,0,&t);
 46:   }
 47:   return 0;
 48: }

 50: /*
 51:   NEPGetDefaultShift - Return the value of sigma to start the nonlinear iteration.
 52:  */
 53: PetscErrorCode NEPGetDefaultShift(NEP nep,PetscScalar *sigma)
 54: {
 56:   switch (nep->which) {
 57:     case NEP_LARGEST_MAGNITUDE:
 58:     case NEP_LARGEST_IMAGINARY:
 59:     case NEP_ALL:
 60:     case NEP_WHICH_USER:
 61:       *sigma = 1.0;   /* arbitrary value */
 62:       break;
 63:     case NEP_SMALLEST_MAGNITUDE:
 64:     case NEP_SMALLEST_IMAGINARY:
 65:       *sigma = 0.0;
 66:       break;
 67:     case NEP_LARGEST_REAL:
 68:       *sigma = PETSC_MAX_REAL;
 69:       break;
 70:     case NEP_SMALLEST_REAL:
 71:       *sigma = PETSC_MIN_REAL;
 72:       break;
 73:     case NEP_TARGET_MAGNITUDE:
 74:     case NEP_TARGET_REAL:
 75:     case NEP_TARGET_IMAGINARY:
 76:       *sigma = nep->target;
 77:       break;
 78:   }
 79:   return 0;
 80: }

 82: /*
 83:   NEPConvergedRelative - Checks convergence relative to the eigenvalue.
 84: */
 85: PetscErrorCode NEPConvergedRelative(NEP nep,PetscScalar eigr,PetscScalar eigi,PetscReal res,PetscReal *errest,void *ctx)
 86: {
 87:   PetscReal w;

 89:   w = SlepcAbsEigenvalue(eigr,eigi);
 90:   *errest = res/w;
 91:   return 0;
 92: }

 94: /*
 95:   NEPConvergedAbsolute - Checks convergence absolutely.
 96: */
 97: PetscErrorCode NEPConvergedAbsolute(NEP nep,PetscScalar eigr,PetscScalar eigi,PetscReal res,PetscReal *errest,void *ctx)
 98: {
 99:   *errest = res;
100:   return 0;
101: }

103: /*
104:   NEPConvergedNorm - Checks convergence relative to the matrix norms.
105: */
106: PetscErrorCode NEPConvergedNorm(NEP nep,PetscScalar eigr,PetscScalar eigi,PetscReal res,PetscReal *errest,void *ctx)
107: {
108:   PetscScalar    s;
109:   PetscReal      w=0.0;
110:   PetscInt       j;
111:   PetscBool      flg;

113:   if (nep->fui!=NEP_USER_INTERFACE_SPLIT) {
114:     NEPComputeFunction(nep,eigr,nep->function,nep->function);
115:     MatHasOperation(nep->function,MATOP_NORM,&flg);
117:     MatNorm(nep->function,NORM_INFINITY,&w);
118:   } else {
119:     /* initialization of matrix norms */
120:     if (!nep->nrma[0]) {
121:       for (j=0;j<nep->nt;j++) {
122:         MatHasOperation(nep->A[j],MATOP_NORM,&flg);
124:         MatNorm(nep->A[j],NORM_INFINITY,&nep->nrma[j]);
125:       }
126:     }
127:     for (j=0;j<nep->nt;j++) {
128:       FNEvaluateFunction(nep->f[j],eigr,&s);
129:       w = w + nep->nrma[j]*PetscAbsScalar(s);
130:     }
131:   }
132:   *errest = res/w;
133:   return 0;
134: }

136: /*@C
137:    NEPStoppingBasic - Default routine to determine whether the outer eigensolver
138:    iteration must be stopped.

140:    Collective on nep

142:    Input Parameters:
143: +  nep    - nonlinear eigensolver context obtained from NEPCreate()
144: .  its    - current number of iterations
145: .  max_it - maximum number of iterations
146: .  nconv  - number of currently converged eigenpairs
147: .  nev    - number of requested eigenpairs
148: -  ctx    - context (not used here)

150:    Output Parameter:
151: .  reason - result of the stopping test

153:    Notes:
154:    A positive value of reason indicates that the iteration has finished successfully
155:    (converged), and a negative value indicates an error condition (diverged). If
156:    the iteration needs to be continued, reason must be set to NEP_CONVERGED_ITERATING
157:    (zero).

159:    NEPStoppingBasic() will stop if all requested eigenvalues are converged, or if
160:    the maximum number of iterations has been reached.

162:    Use NEPSetStoppingTest() to provide your own test instead of using this one.

164:    Level: advanced

166: .seealso: NEPSetStoppingTest(), NEPConvergedReason, NEPGetConvergedReason()
167: @*/
168: PetscErrorCode NEPStoppingBasic(NEP nep,PetscInt its,PetscInt max_it,PetscInt nconv,PetscInt nev,NEPConvergedReason *reason,void *ctx)
169: {
170:   *reason = NEP_CONVERGED_ITERATING;
171:   if (nconv >= nev) {
172:     PetscInfo(nep,"Nonlinear eigensolver finished successfully: %" PetscInt_FMT " eigenpairs converged at iteration %" PetscInt_FMT "\n",nconv,its);
173:     *reason = NEP_CONVERGED_TOL;
174:   } else if (its >= max_it) {
175:     *reason = NEP_DIVERGED_ITS;
176:     PetscInfo(nep,"Nonlinear eigensolver iteration reached maximum number of iterations (%" PetscInt_FMT ")\n",its);
177:   }
178:   return 0;
179: }

181: PetscErrorCode NEPComputeVectors_Schur(NEP nep)
182: {
183:   Mat            Z;

185:   DSVectors(nep->ds,DS_MAT_X,NULL,NULL);
186:   DSGetMat(nep->ds,DS_MAT_X,&Z);
187:   BVMultInPlace(nep->V,Z,0,nep->nconv);
188:   DSRestoreMat(nep->ds,DS_MAT_X,&Z);
189:   BVNormalize(nep->V,nep->eigi);
190:   return 0;
191: }