Date: 2026-05-01T10:02:27+00:00

Actual source code: nleigs.h

      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:    Private header for NLEIGS
     12: */

     14: #pragma once

     16: #define  LBPOINTS  100   /* default value of the maximum number of Leja-Bagby points */
     17: #define  NDPOINTS  1e4   /* number of discretization points */

     19: typedef struct {
     20:   BV             V;         /* tensor vector basis for the linearization */
     21:   BV             W;         /* tensor vector basis for the linearization */
     22:   PetscInt       nmat;      /* number of interpolation points */
     23:   PetscScalar    *s,*xi;    /* Leja-Bagby points */
     24:   PetscScalar    *beta;     /* scaling factors */
     25:   Mat            *D;        /* divided difference matrices */
     26:   PetscScalar    *coeffD;   /* coefficients for divided differences in split form */
     27:   PetscInt       nshifts;   /* provided number of shifts */
     28:   PetscScalar    *shifts;   /* user-provided shifts for the Rational Krylov variant */
     29:   PetscInt       nshiftsw;  /* actual number of shifts (1 if Krylov-Schur) */
     30:   PetscReal      ddtol;     /* tolerance for divided difference convergence */
     31:   PetscInt       ddmaxit;   /* maximum number of divided difference terms */
     32:   PetscReal      keep;      /* restart parameter */
     33:   PetscBool      lock;      /* locking/non-locking variant */
     34:   PetscInt       idxrk;     /* index of next shift to use */
     35:   KSP            *ksp;      /* ksp array for storing shift factorizations */
     36:   Vec            vrn;       /* random vector with normally distributed value */
     37:   PetscBool      fullbasis; /* use full Krylov basis instead of TOAR basis */
     38:   EPS            eps;       /* eigensolver used in the full basis variant */
     39:   Mat            A;         /* shell matrix used for the eps in full basis */
     40:   Vec            w[6];      /* work vectors */
     41:   void           *singularitiesctx;
     42:   PetscErrorCode (*computesingularities)(NEP,PetscInt*,PetscScalar*,void*);
     43: } NEP_NLEIGS;

     45: typedef struct {
     46:   PetscInt    nmat,maxnmat;
     47:   PetscScalar *coeff;
     48:   Mat         *A;
     49:   Vec         t;
     50: } NEP_NLEIGS_MATSHELL;

     52: static inline PetscErrorCode NEPNLEIGSSetShifts(NEP nep,PetscInt *nshiftsw)
     53: {
     54:   NEP_NLEIGS *ctx = (NEP_NLEIGS*)nep->data;

     56:   PetscFunctionBegin;
     57:   if (!ctx->nshifts) {
     58:     ctx->shifts = &nep->target;
     59:     *nshiftsw = 1;
     60:   } else *nshiftsw = ctx->nshifts;
     61:   PetscFunctionReturn(PETSC_SUCCESS);
     62: }

     64: SLEPC_INTERN PetscErrorCode NEPSetUp_NLEIGS_FullBasis(NEP);
     65: SLEPC_INTERN PetscErrorCode NEPNLEIGSSetEPS_NLEIGS(NEP,EPS);
     66: SLEPC_INTERN PetscErrorCode NEPNLEIGSGetEPS_NLEIGS(NEP,EPS*);
     67: SLEPC_INTERN PetscErrorCode NEPNLEIGSBackTransform(PetscObject,PetscInt,PetscScalar*,PetscScalar *vali);
     68: SLEPC_INTERN PetscErrorCode NEPNLEIGSEvalNRTFunct(NEP,PetscInt,PetscScalar,PetscScalar*);
     69: SLEPC_INTERN PetscErrorCode NEPSolve_NLEIGS_FullBasis(NEP);
     70: SLEPC_INTERN PetscErrorCode NEPSolve_NLEIGS(NEP);