Date: 2021-02-01T14:42:01+00:00

Actual source code: test39.c
slepc-3.14.2 2021-02-01
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      1: /*
      2:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      3:    SLEPc - Scalable Library for Eigenvalue Problem Computations
      4:    Copyright (c) 2002-2020, 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[] = "Tests multiple calls to EPSSolve with matrices of different local size.\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: /*
     19:    Create 2-D Laplacian matrix
     20: */
     21: PetscErrorCode Laplacian(MPI_Comm comm,PetscInt n,PetscInt m,PetscInt shift,Mat *A)
     22: {
     24:   PetscInt       N = n*m,i,j,II,Istart,Iend,nloc;
     25:   PetscMPIInt    rank;

     28:   MPI_Comm_rank(PETSC_COMM_WORLD,&rank);
     29:   nloc = PETSC_DECIDE;
     30:   PetscSplitOwnership(comm,&nloc,&N);
     31:   if (rank==0) nloc += shift;
     32:   else if (rank==1) nloc -= shift;

     34:   MatCreate(comm,A);
     35:   MatSetSizes(*A,nloc,nloc,N,N);
     36:   MatSetFromOptions(*A);
     37:   MatSetUp(*A);
     38:   MatGetOwnershipRange(*A,&Istart,&Iend);
     39:   for (II=Istart;II<Iend;II++) {
     40:     i = II/n; j = II-i*n;
     41:     if (i>0) { MatSetValue(*A,II,II-n,-1.0,INSERT_VALUES); }
     42:     if (i<m-1) { MatSetValue(*A,II,II+n,-1.0,INSERT_VALUES); }
     43:     if (j>0) { MatSetValue(*A,II,II-1,-1.0,INSERT_VALUES); }
     44:     if (j<n-1) { MatSetValue(*A,II,II+1,-1.0,INSERT_VALUES); }
     45:     MatSetValue(*A,II,II,4.0,INSERT_VALUES);
     46:   }
     47:   MatAssemblyBegin(*A,MAT_FINAL_ASSEMBLY);
     48:   MatAssemblyEnd(*A,MAT_FINAL_ASSEMBLY);
     49:   return(0);
     50: }

     52: int main(int argc,char **argv)
     53: {
     54:   Mat            A,B;
     55:   EPS            eps;
     56:   PetscInt       N,n=10,m=11,nev=3;
     57:   PetscMPIInt    size;
     58:   PetscBool      flag,terse;

     61:   SlepcInitialize(&argc,&argv,(char*)0,help);if (ierr) return ierr;
     62:   MPI_Comm_size(PETSC_COMM_WORLD,&size);
     63:   if (size==1) SETERRQ(PETSC_COMM_WORLD,PETSC_ERR_WRONG_MPI_SIZE,"This example requires at least two processes");
     64:   PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL);
     65:   PetscOptionsGetInt(NULL,NULL,"-m",&m,&flag);
     66:   N = n*m;
     67:   PetscPrintf(PETSC_COMM_WORLD,"\n2-D Laplacian Eigenproblem, N=%D (%Dx%D grid)\n\n",N,n,m);

     69:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     70:                 Create 2-D Laplacian matrices
     71:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

     73:   Laplacian(PETSC_COMM_WORLD,n,m,1,&A);
     74:   Laplacian(PETSC_COMM_WORLD,n,m,-1,&B);

     76:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     77:         Create the eigensolver, set options and solve the eigensystem
     78:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

     80:   PetscPrintf(PETSC_COMM_WORLD,"First solve:\n\n");
     81:   EPSCreate(PETSC_COMM_WORLD,&eps);
     82:   EPSSetOperators(eps,A,NULL);
     83:   EPSSetProblemType(eps,EPS_HEP);
     84:   EPSSetWhichEigenpairs(eps,EPS_SMALLEST_REAL);
     85:   EPSSetDimensions(eps,nev,PETSC_DEFAULT,PETSC_DEFAULT);
     86:   EPSSetFromOptions(eps);

     88:   EPSSolve(eps);

     90:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     91:                     Display solution of first solve
     92:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

     94:   PetscOptionsHasName(NULL,NULL,"-terse",&terse);
     95:   if (terse) {
     96:     EPSErrorView(eps,EPS_ERROR_RELATIVE,NULL);
     97:   } else {
     98:     PetscViewerPushFormat(PETSC_VIEWER_STDOUT_WORLD,PETSC_VIEWER_ASCII_INFO_DETAIL);
     99:     EPSConvergedReasonView(eps,PETSC_VIEWER_STDOUT_WORLD);
    100:     EPSErrorView(eps,EPS_ERROR_RELATIVE,PETSC_VIEWER_STDOUT_WORLD);
    101:     PetscViewerPopFormat(PETSC_VIEWER_STDOUT_WORLD);
    102:   }

    104:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    105:                        Solve with second matrix
    106:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

    108:   PetscPrintf(PETSC_COMM_WORLD,"\nSecond solve:\n\n");
    109:   /*EPSReset(eps);*/  /* not required, will be called in EPSSetOperators() */
    110:   EPSSetOperators(eps,B,NULL);
    111:   EPSSolve(eps);

    113:   if (terse) {
    114:     EPSErrorView(eps,EPS_ERROR_RELATIVE,NULL);
    115:   } else {
    116:     PetscViewerPushFormat(PETSC_VIEWER_STDOUT_WORLD,PETSC_VIEWER_ASCII_INFO_DETAIL);
    117:     EPSConvergedReasonView(eps,PETSC_VIEWER_STDOUT_WORLD);
    118:     EPSErrorView(eps,EPS_ERROR_RELATIVE,PETSC_VIEWER_STDOUT_WORLD);
    119:     PetscViewerPopFormat(PETSC_VIEWER_STDOUT_WORLD);
    120:   }

    122:   EPSDestroy(&eps);
    123:   MatDestroy(&A);
    124:   MatDestroy(&B);
    125:   SlepcFinalize();
    126:   return ierr;
    127: }

    129: /*TEST

    131:    test:
    132:       suffix: 1
    133:       nsize: 2
    134:       args: -eps_type {{krylovschur arnoldi lanczos lobpcg lapack}} -terse
    135:       requires: !single

    137: TEST*/