Date: 2022-10-01T06:39:58+00:00

Actual source code: test4.c
slepc-3.18.0 2022-10-01
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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: */

     11: static char help[] = "Test the solution of a HEP without calling EPSSetFromOptions (based on ex1.c).\n\n"
     12:   "The command line options are:\n"
     13:   "  -n <n>, where <n> = number of grid subdivisions = matrix dimension.\n"
     14:   "  -type <eps_type> = eps type to test.\n\n";

     16: #include <slepceps.h>

     18: int main(int argc,char **argv)
     19: {
     20:   Mat            A;           /* problem matrix */
     21:   EPS            eps;         /* eigenproblem solver context */
     22:   PetscReal      tol=1000*PETSC_MACHINE_EPSILON;
     23:   PetscInt       n=30,i,Istart,Iend,nev;
     24:   PetscBool      flg,gd2;
     25:   char           epstype[30] = "krylovschur";

     28:   SlepcInitialize(&argc,&argv,(char*)0,help);

     30:   PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL);
     31:   PetscOptionsGetString(NULL,NULL,"-type",epstype,sizeof(epstype),NULL);
     32:   PetscPrintf(PETSC_COMM_WORLD,"\n1-D Laplacian Eigenproblem, n=%" PetscInt_FMT "\n\n",n);

     34:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     35:      Compute the operator matrix that defines the eigensystem, Ax=kx
     36:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

     38:   MatCreate(PETSC_COMM_WORLD,&A);
     39:   MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,n,n);
     40:   MatSetFromOptions(A);
     41:   MatSetUp(A);

     43:   MatGetOwnershipRange(A,&Istart,&Iend);
     44:   for (i=Istart;i<Iend;i++) {
     45:     if (i>0) MatSetValue(A,i,i-1,-1.0,INSERT_VALUES);
     46:     if (i<n-1) MatSetValue(A,i,i+1,-1.0,INSERT_VALUES);
     47:     MatSetValue(A,i,i,2.0,INSERT_VALUES);
     48:   }
     49:   MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
     50:   MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);

     52:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     53:                 Create the eigensolver and set various options
     54:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
     55:   /*
     56:      Create eigensolver context
     57:   */
     58:   EPSCreate(PETSC_COMM_WORLD,&eps);

     60:   /*
     61:      Set operators. In this case, it is a standard eigenvalue problem
     62:   */
     63:   EPSSetOperators(eps,A,NULL);
     64:   EPSSetProblemType(eps,EPS_HEP);
     65:   EPSSetDimensions(eps,4,PETSC_DEFAULT,PETSC_DEFAULT);
     66:   EPSSetTolerances(eps,tol,PETSC_DEFAULT);

     68:   /*
     69:      Set solver parameters at runtime
     70:   */
     71:   PetscStrcmp(epstype,"gd2",&flg);
     72:   if (flg) {
     73:     EPSSetType(eps,EPSGD);
     74:     EPSGDSetDoubleExpansion(eps,PETSC_TRUE);
     75:     EPSGDGetDoubleExpansion(eps,&gd2);  /* not used */
     76:   } else EPSSetType(eps,epstype);
     77:   PetscStrcmp(epstype,"jd",&flg);
     78:   if (flg) {
     79:     EPSSetWhichEigenpairs(eps,EPS_TARGET_MAGNITUDE);
     80:     EPSSetTarget(eps,4.0);
     81:   }
     82:   PetscStrcmp(epstype,"lanczos",&flg);
     83:   if (flg) EPSLanczosSetReorthog(eps,EPS_LANCZOS_REORTHOG_LOCAL);
     84:   PetscObjectTypeCompareAny((PetscObject)eps,&flg,EPSRQCG,EPSLOBPCG,"");
     85:   if (flg) EPSSetWhichEigenpairs(eps,EPS_SMALLEST_REAL);

     87:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     88:                       Solve the eigensystem
     89:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

     91:   EPSSolve(eps);
     92:   EPSGetDimensions(eps,&nev,NULL,NULL);
     93:   PetscPrintf(PETSC_COMM_WORLD," Number of requested eigenvalues: %" PetscInt_FMT "\n",nev);

     95:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     96:                     Display solution and clean up
     97:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

     99:   EPSErrorView(eps,EPS_ERROR_RELATIVE,NULL);
    100:   EPSDestroy(&eps);
    101:   MatDestroy(&A);
    102:   SlepcFinalize();
    103:   return 0;
    104: }

    106: /*TEST

    108:    testset:
    109:       output_file: output/test4_1.out
    110:       test:
    111:          suffix: 1
    112:          args: -type {{krylovschur subspace arnoldi lanczos gd jd gd2 lapack}}
    113:       test:
    114:          suffix: 1_arpack
    115:          args: -type arpack
    116:          requires: arpack
    117:       test:
    118:          suffix: 1_primme
    119:          args: -type primme
    120:          requires: primme
    121:       test:
    122:          suffix: 1_trlan
    123:          args: -type trlan
    124:          requires: trlan

    126:    test:
    127:       suffix: 2
    128:       args: -type {{rqcg lobpcg}}

    130: TEST*/