Date: 2022-08-09T09:05:41+00:00

Actual source code: ex13.c
slepc-3.17.2 2022-08-09
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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[] = "Generalized Symmetric eigenproblem.\n\n"
     12:   "The problem is Ax = lambda Bx, with:\n"
     13:   "   A = Laplacian operator in 2-D\n"
     14:   "   B = diagonal matrix with all values equal to 4 except nulldim zeros\n\n"
     15:   "The command line options are:\n"
     16:   "  -n <n>, where <n> = number of grid subdivisions in x dimension.\n"
     17:   "  -m <m>, where <m> = number of grid subdivisions in y dimension.\n"
     18:   "  -nulldim <k>, where <k> = dimension of the nullspace of B.\n\n";

     20: #include <slepceps.h>

     22: int main(int argc,char **argv)
     23: {
     24:   Mat            A,B;         /* matrices */
     25:   EPS            eps;         /* eigenproblem solver context */
     26:   EPSType        type;
     27:   PetscInt       N,n=10,m,Istart,Iend,II,nev,i,j,nulldim=0;
     28:   PetscBool      flag,terse;

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

     32:   PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL);
     33:   PetscOptionsGetInt(NULL,NULL,"-m",&m,&flag);
     34:   if (!flag) m=n;
     35:   N = n*m;
     36:   PetscOptionsGetInt(NULL,NULL,"-nulldim",&nulldim,NULL);
     37:   PetscPrintf(PETSC_COMM_WORLD,"\nGeneralized Symmetric Eigenproblem, N=%" PetscInt_FMT " (%" PetscInt_FMT "x%" PetscInt_FMT " grid), null(B)=%" PetscInt_FMT "\n\n",N,n,m,nulldim);

     39:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     40:      Compute the matrices that define the eigensystem, Ax=kBx
     41:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

     43:   MatCreate(PETSC_COMM_WORLD,&A);
     44:   MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,N,N);
     45:   MatSetFromOptions(A);
     46:   MatSetUp(A);

     48:   MatCreate(PETSC_COMM_WORLD,&B);
     49:   MatSetSizes(B,PETSC_DECIDE,PETSC_DECIDE,N,N);
     50:   MatSetFromOptions(B);
     51:   MatSetUp(B);

     53:   MatGetOwnershipRange(A,&Istart,&Iend);
     54:   for (II=Istart;II<Iend;II++) {
     55:     i = II/n; j = II-i*n;
     56:     if (i>0) MatSetValue(A,II,II-n,-1.0,INSERT_VALUES);
     57:     if (i<m-1) MatSetValue(A,II,II+n,-1.0,INSERT_VALUES);
     58:     if (j>0) MatSetValue(A,II,II-1,-1.0,INSERT_VALUES);
     59:     if (j<n-1) MatSetValue(A,II,II+1,-1.0,INSERT_VALUES);
     60:     MatSetValue(A,II,II,4.0,INSERT_VALUES);
     61:     if (II>=nulldim) MatSetValue(B,II,II,4.0,INSERT_VALUES);
     62:   }

     64:   MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
     65:   MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);
     66:   MatAssemblyBegin(B,MAT_FINAL_ASSEMBLY);
     67:   MatAssemblyEnd(B,MAT_FINAL_ASSEMBLY);

     69:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     70:                 Create the eigensolver and set various options
     71:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

     73:   /*
     74:      Create eigensolver context
     75:   */
     76:   EPSCreate(PETSC_COMM_WORLD,&eps);

     78:   /*
     79:      Set operators. In this case, it is a generalized eigenvalue problem
     80:   */
     81:   EPSSetOperators(eps,A,B);
     82:   EPSSetProblemType(eps,EPS_GHEP);

     84:   /*
     85:      Set solver parameters at runtime
     86:   */
     87:   EPSSetFromOptions(eps);

     89:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     90:                       Solve the eigensystem
     91:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

     93:   EPSSolve(eps);

     95:   /*
     96:      Optional: Get some information from the solver and display it
     97:   */
     98:   EPSGetType(eps,&type);
     99:   PetscPrintf(PETSC_COMM_WORLD," Solution method: %s\n\n",type);
    100:   EPSGetDimensions(eps,&nev,NULL,NULL);
    101:   PetscPrintf(PETSC_COMM_WORLD," Number of requested eigenvalues: %" PetscInt_FMT "\n",nev);

    103:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    104:                     Display solution and clean up
    105:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

    107:   /* show detailed info unless -terse option is given by user */
    108:   PetscOptionsHasName(NULL,NULL,"-terse",&terse);
    109:   if (terse) EPSErrorView(eps,EPS_ERROR_RELATIVE,NULL);
    110:   else {
    111:     PetscViewerPushFormat(PETSC_VIEWER_STDOUT_WORLD,PETSC_VIEWER_ASCII_INFO_DETAIL);
    112:     EPSConvergedReasonView(eps,PETSC_VIEWER_STDOUT_WORLD);
    113:     EPSErrorView(eps,EPS_ERROR_RELATIVE,PETSC_VIEWER_STDOUT_WORLD);
    114:     PetscViewerPopFormat(PETSC_VIEWER_STDOUT_WORLD);
    115:   }
    116:   EPSDestroy(&eps);
    117:   MatDestroy(&A);
    118:   MatDestroy(&B);
    119:   SlepcFinalize();
    120:   return 0;
    121: }

    123: /*TEST

    125:    test:
    126:       suffix: 1
    127:       args: -eps_nev 4 -eps_ncv 22 -eps_tol 1e-5 -st_type sinvert -terse
    128:       filter: grep -v Solution

    130:    test:
    131:       suffix: 2
    132:       args: -n 110 -nulldim 6 -eps_nev 4 -eps_ncv 18 -eps_tol 1e-5 -eps_purify 1 -st_type sinvert -st_matstructure {{different subset}} -terse
    133:       requires: !single

    135:    test:
    136:       suffix: 3
    137:       args: -eps_nev 3 -eps_tol 1e-5 -mat_type sbaij -st_type sinvert -terse

    139:    test:
    140:       suffix: 4
    141:       args: -eps_nev 4 -eps_tol 1e-4 -eps_smallest_real -eps_type {{gd lobpcg rqcg}} -terse
    142:       output_file: output/ex13_1.out
    143:       filter: grep -v Solution

    145:    test:
    146:       suffix: 5_primme
    147:       args: -n 10 -m 12 -eps_nev 4 -eps_target 0.9 -eps_max_it 15000 -eps_type primme -st_pc_type jacobi -terse
    148:       requires: primme defined(SLEPC_HAVE_PRIMME3) !single

    150:    test:
    151:       suffix: 6
    152:       nsize: 2
    153:       args: -eps_type ciss -rg_type ellipse -rg_ellipse_center 1.4 -rg_ellipse_radius 0.1 -eps_ciss_partitions 2 -terse
    154:       requires: !single

    156: TEST*/