Date: 2026-01-20T11:35:39+00:00

Actual source code: test30.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: */

     11: static char help[] = "Test changing EPS type.\n\n";

     13: #include <slepceps.h>

     15: int main(int argc,char **argv)
     16: {
     17:   Mat            A;           /* problem matrix */
     18:   EPS            eps;         /* eigenproblem solver context */
     19:   ST             st;
     20:   KSP            ksp;
     21:   PetscInt       n=20,i,Istart,Iend,nrest;

     23:   PetscFunctionBeginUser;
     24:   PetscCall(SlepcInitialize(&argc,&argv,NULL,help));
     25:   PetscCall(PetscPrintf(PETSC_COMM_WORLD,"\nDiagonal Eigenproblem, n=%" PetscInt_FMT "\n\n",n));

     27:   PetscCall(MatCreate(PETSC_COMM_WORLD,&A));
     28:   PetscCall(MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,n,n));
     29:   PetscCall(MatSetFromOptions(A));
     30:   PetscCall(MatGetOwnershipRange(A,&Istart,&Iend));
     31:   for (i=Istart;i<Iend;i++) PetscCall(MatSetValue(A,i,i,i+1,INSERT_VALUES));
     32:   PetscCall(MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY));
     33:   PetscCall(MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY));

     35:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     36:              Create eigensolver and view options
     37:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
     38:   PetscCall(EPSCreate(PETSC_COMM_WORLD,&eps));
     39:   PetscCall(EPSSetOperators(eps,A,NULL));
     40:   PetscCall(EPSSetProblemType(eps,EPS_HEP));
     41:   PetscCall(EPSSetTarget(eps,4.8));
     42:   PetscCall(EPSSetWhichEigenpairs(eps,EPS_TARGET_MAGNITUDE));
     43:   PetscCall(EPSSetDimensions(eps,4,PETSC_DETERMINE,PETSC_DETERMINE));

     45:   PetscCall(EPSSetType(eps,EPSRQCG));
     46:   PetscCall(EPSRQCGSetReset(eps,10));
     47:   PetscCall(EPSSetFromOptions(eps));
     48:   PetscCall(EPSRQCGGetReset(eps,&nrest));
     49:   PetscCall(PetscPrintf(PETSC_COMM_WORLD,"RQCG reset parameter = %" PetscInt_FMT "\n\n",nrest));
     50:   PetscCall(EPSView(eps,NULL));

     52:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     53:              Change eigensolver type and solve problem
     54:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
     55:   PetscCall(EPSSetType(eps,EPSGD));
     56:   PetscCall(EPSGetST(eps,&st));
     57:   PetscCall(STGetKSP(st,&ksp));
     58:   PetscCall(KSPSetType(ksp,KSPPREONLY));
     59:   PetscCall(EPSSolve(eps));
     60:   PetscCall(EPSView(eps,NULL));

     62:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     63:                     Display solution and clean up
     64:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
     65:   PetscCall(EPSErrorView(eps,EPS_ERROR_RELATIVE,NULL));
     66:   PetscCall(EPSDestroy(&eps));
     67:   PetscCall(MatDestroy(&A));
     68:   PetscCall(SlepcFinalize());
     69:   return 0;
     70: }

     72: /*TEST

     74:    test:
     75:       suffix: 1
     76:       args: -eps_harmonic -eps_conv_norm
     77:       filter: grep -v tolerance | sed -e "s/symmetric/hermitian/"

     79: TEST*/