Actual source code: nepdefault.c
slepc-3.18.0 2022-10-01
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;
37: if (nep->nwork < nw) {
38: VecDestroyVecs(nep->nwork,&nep->work);
39: nep->nwork = nw;
40: BVGetColumn(nep->V,0,&t);
41: VecDuplicateVecs(t,nw,&nep->work);
42: BVRestoreColumn(nep->V,0,&t);
43: }
44: return 0;
45: }
47: /*
48: NEPGetDefaultShift - Return the value of sigma to start the nonlinear iteration.
49: */
50: PetscErrorCode NEPGetDefaultShift(NEP nep,PetscScalar *sigma)
51: {
53: switch (nep->which) {
54: case NEP_LARGEST_MAGNITUDE:
55: case NEP_LARGEST_IMAGINARY:
56: case NEP_ALL:
57: case NEP_WHICH_USER:
58: *sigma = 1.0; /* arbitrary value */
59: break;
60: case NEP_SMALLEST_MAGNITUDE:
61: case NEP_SMALLEST_IMAGINARY:
62: *sigma = 0.0;
63: break;
64: case NEP_LARGEST_REAL:
65: *sigma = PETSC_MAX_REAL;
66: break;
67: case NEP_SMALLEST_REAL:
68: *sigma = PETSC_MIN_REAL;
69: break;
70: case NEP_TARGET_MAGNITUDE:
71: case NEP_TARGET_REAL:
72: case NEP_TARGET_IMAGINARY:
73: *sigma = nep->target;
74: break;
75: }
76: return 0;
77: }
79: /*
80: NEPConvergedRelative - Checks convergence relative to the eigenvalue.
81: */
82: PetscErrorCode NEPConvergedRelative(NEP nep,PetscScalar eigr,PetscScalar eigi,PetscReal res,PetscReal *errest,void *ctx)
83: {
84: PetscReal w;
86: w = SlepcAbsEigenvalue(eigr,eigi);
87: *errest = res/w;
88: return 0;
89: }
91: /*
92: NEPConvergedAbsolute - Checks convergence absolutely.
93: */
94: PetscErrorCode NEPConvergedAbsolute(NEP nep,PetscScalar eigr,PetscScalar eigi,PetscReal res,PetscReal *errest,void *ctx)
95: {
96: *errest = res;
97: return 0;
98: }
100: /*
101: NEPConvergedNorm - Checks convergence relative to the matrix norms.
102: */
103: PetscErrorCode NEPConvergedNorm(NEP nep,PetscScalar eigr,PetscScalar eigi,PetscReal res,PetscReal *errest,void *ctx)
104: {
105: PetscScalar s;
106: PetscReal w=0.0;
107: PetscInt j;
108: PetscBool flg;
110: if (nep->fui!=NEP_USER_INTERFACE_SPLIT) {
111: NEPComputeFunction(nep,eigr,nep->function,nep->function);
112: MatHasOperation(nep->function,MATOP_NORM,&flg);
114: MatNorm(nep->function,NORM_INFINITY,&w);
115: } else {
116: /* initialization of matrix norms */
117: if (!nep->nrma[0]) {
118: for (j=0;j<nep->nt;j++) {
119: MatHasOperation(nep->A[j],MATOP_NORM,&flg);
121: MatNorm(nep->A[j],NORM_INFINITY,&nep->nrma[j]);
122: }
123: }
124: for (j=0;j<nep->nt;j++) {
125: FNEvaluateFunction(nep->f[j],eigr,&s);
126: w = w + nep->nrma[j]*PetscAbsScalar(s);
127: }
128: }
129: *errest = res/w;
130: return 0;
131: }
133: /*@C
134: NEPStoppingBasic - Default routine to determine whether the outer eigensolver
135: iteration must be stopped.
137: Collective on nep
139: Input Parameters:
140: + nep - nonlinear eigensolver context obtained from NEPCreate()
141: . its - current number of iterations
142: . max_it - maximum number of iterations
143: . nconv - number of currently converged eigenpairs
144: . nev - number of requested eigenpairs
145: - ctx - context (not used here)
147: Output Parameter:
148: . reason - result of the stopping test
150: Notes:
151: A positive value of reason indicates that the iteration has finished successfully
152: (converged), and a negative value indicates an error condition (diverged). If
153: the iteration needs to be continued, reason must be set to NEP_CONVERGED_ITERATING
154: (zero).
156: NEPStoppingBasic() will stop if all requested eigenvalues are converged, or if
157: the maximum number of iterations has been reached.
159: Use NEPSetStoppingTest() to provide your own test instead of using this one.
161: Level: advanced
163: .seealso: NEPSetStoppingTest(), NEPConvergedReason, NEPGetConvergedReason()
164: @*/
165: PetscErrorCode NEPStoppingBasic(NEP nep,PetscInt its,PetscInt max_it,PetscInt nconv,PetscInt nev,NEPConvergedReason *reason,void *ctx)
166: {
167: *reason = NEP_CONVERGED_ITERATING;
168: if (nconv >= nev) {
169: PetscInfo(nep,"Nonlinear eigensolver finished successfully: %" PetscInt_FMT " eigenpairs converged at iteration %" PetscInt_FMT "\n",nconv,its);
170: *reason = NEP_CONVERGED_TOL;
171: } else if (its >= max_it) {
172: *reason = NEP_DIVERGED_ITS;
173: PetscInfo(nep,"Nonlinear eigensolver iteration reached maximum number of iterations (%" PetscInt_FMT ")\n",its);
174: }
175: return 0;
176: }
178: PetscErrorCode NEPComputeVectors_Schur(NEP nep)
179: {
180: Mat Z;
182: DSVectors(nep->ds,DS_MAT_X,NULL,NULL);
183: DSGetMat(nep->ds,DS_MAT_X,&Z);
184: BVMultInPlace(nep->V,Z,0,nep->nconv);
185: DSRestoreMat(nep->ds,DS_MAT_X,&Z);
186: BVNormalize(nep->V,nep->eigi);
187: return 0;
188: }