Actual source code: ex2.c
slepc-3.10.1 2018-10-23
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      1: /*
      2:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      3:    SLEPc - Scalable Library for Eigenvalue Problem Computations
      4:    Copyright (c) 2002-2018, 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[] = "Standard symmetric eigenproblem corresponding to the Laplacian operator in 2 dimensions.\n\n"
     12:   "The command line options are:\n"
     13:   "  -n <n>, where <n> = number of grid subdivisions in x dimension.\n"
     14:   "  -m <m>, where <m> = number of grid subdivisions in y dimension.\n\n";

     16: #include <slepceps.h>

     18: int main(int argc,char **argv)
     19: {
     20:   Mat            A;               /* operator matrix */
     21:   EPS            eps;             /* eigenproblem solver context */
     22:   EPSType        type;
     23:   PetscInt       N,n=10,m,Istart,Iend,II,nev,i,j;
     24:   PetscBool      flag,terse;

     27:   SlepcInitialize(&argc,&argv,(char*)0,help);if (ierr) return ierr;

     29:   PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL);
     30:   PetscOptionsGetInt(NULL,NULL,"-m",&m,&flag);
     31:   if (!flag) m=n;
     32:   N = n*m;
     33:   PetscPrintf(PETSC_COMM_WORLD,"\n2-D Laplacian Eigenproblem, N=%D (%Dx%D grid)\n\n",N,n,m);

     35:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     36:      Compute the operator matrix that defines the eigensystem, Ax=kx
     37:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

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

     44:   MatGetOwnershipRange(A,&Istart,&Iend);
     45:   for (II=Istart;II<Iend;II++) {
     46:     i = II/n; j = II-i*n;
     47:     if (i>0) { MatSetValue(A,II,II-n,-1.0,INSERT_VALUES); }
     48:     if (i<m-1) { MatSetValue(A,II,II+n,-1.0,INSERT_VALUES); }
     49:     if (j>0) { MatSetValue(A,II,II-1,-1.0,INSERT_VALUES); }
     50:     if (j<n-1) { MatSetValue(A,II,II+1,-1.0,INSERT_VALUES); }
     51:     MatSetValue(A,II,II,4.0,INSERT_VALUES);
     52:   }

     54:   MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
     55:   MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);

     57:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     58:                 Create the eigensolver and set various options
     59:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

     61:   /*
     62:      Create eigensolver context
     63:   */
     64:   EPSCreate(PETSC_COMM_WORLD,&eps);

     66:   /*
     67:      Set operators. In this case, it is a standard eigenvalue problem
     68:   */
     69:   EPSSetOperators(eps,A,NULL);
     70:   EPSSetProblemType(eps,EPS_HEP);

     72:   /*
     73:      Set solver parameters at runtime
     74:   */
     75:   EPSSetFromOptions(eps);

     77:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     78:                       Solve the eigensystem
     79:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

     81:   EPSSolve(eps);

     83:   /*
     84:      Optional: Get some information from the solver and display it
     85:   */
     86:   EPSGetType(eps,&type);
     87:   PetscPrintf(PETSC_COMM_WORLD," Solution method: %s\n\n",type);
     88:   EPSGetDimensions(eps,&nev,NULL,NULL);
     89:   PetscPrintf(PETSC_COMM_WORLD," Number of requested eigenvalues: %D\n",nev);

     91:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     92:                     Display solution and clean up
     93:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

     95:   /* show detailed info unless -terse option is given by user */
     96:   PetscOptionsHasName(NULL,NULL,"-terse",&terse);
     97:   if (terse) {
     98:     EPSErrorView(eps,EPS_ERROR_RELATIVE,NULL);
     99:   } else {
    100:     PetscViewerPushFormat(PETSC_VIEWER_STDOUT_WORLD,PETSC_VIEWER_ASCII_INFO_DETAIL);
    101:     EPSReasonView(eps,PETSC_VIEWER_STDOUT_WORLD);
    102:     EPSErrorView(eps,EPS_ERROR_RELATIVE,PETSC_VIEWER_STDOUT_WORLD);
    103:     PetscViewerPopFormat(PETSC_VIEWER_STDOUT_WORLD);
    104:   }
    105:   EPSDestroy(&eps);
    106:   MatDestroy(&A);
    107:   SlepcFinalize();
    108:   return ierr;
    109: }

    111: /*TEST

    113:    testset:
    114:       args: -n 72 -eps_nev 4 -eps_ncv 20 -terse
    115:       requires: !single
    116:       output_file: output/ex2_1.out
    117:       test:
    118:          suffix: 1
    119:       test:
    120:          suffix: 2
    121:          args: -dynamic_library_preload

    123:    testset:
    124:       args: -n 30 -eps_type ciss -terse
    125:       requires: double
    126:       output_file: output/ex2_ciss.out
    127:       test:
    128:          suffix: ciss_1
    129:          nsize: 1
    130:          args: -rg_type interval -rg_interval_endpoints 1.1,1.25
    131:       test:
    132:          suffix: ciss_2
    133:          nsize: 2
    134:          args: -rg_type ellipse -rg_ellipse_center 1.175 -rg_ellipse_radius 0.075 -eps_ciss_partitions 2

    136: TEST*/