Date: 2026-01-20T11:35:38+00:00

Actual source code: test35.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 interface to external package BLOPEX.\n\n"
     12:   "This is based on ex12.c. 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,B;         /* matrices */
     21:   EPS            eps;         /* eigenproblem solver context */
     22:   ST             st;          /* spectral transformation context */
     23:   KSP            ksp;
     24:   PC             pc;
     25:   PetscInt       N,n=35,m,Istart,Iend,II,i,j,bs;
     26:   PetscBool      flag;

     28:   PetscFunctionBeginUser;
     29:   PetscCall(SlepcInitialize(&argc,&argv,NULL,help));

     31:   PetscCall(PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL));
     32:   PetscCall(PetscOptionsGetInt(NULL,NULL,"-m",&m,&flag));
     33:   if (!flag) m=n;
     34:   N = n*m;
     35:   PetscCall(PetscPrintf(PETSC_COMM_WORLD,"\nGeneralized eigenproblem with BLOPEX, N=%" PetscInt_FMT " (%" PetscInt_FMT "x%" PetscInt_FMT " grid)\n\n",N,n,m));

     37:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     38:      Compute the matrices that define the eigensystem, Ax=kBx
     39:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

     41:   PetscCall(MatCreate(PETSC_COMM_WORLD,&A));
     42:   PetscCall(MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,N,N));
     43:   PetscCall(MatSetFromOptions(A));

     45:   PetscCall(MatCreate(PETSC_COMM_WORLD,&B));
     46:   PetscCall(MatSetSizes(B,PETSC_DECIDE,PETSC_DECIDE,N,N));
     47:   PetscCall(MatSetFromOptions(B));

     49:   PetscCall(MatGetOwnershipRange(A,&Istart,&Iend));
     50:   for (II=Istart;II<Iend;II++) {
     51:     i = II/n; j = II-i*n;
     52:     if (i>0) PetscCall(MatSetValue(A,II,II-n,-1.0,INSERT_VALUES));
     53:     if (i<m-1) PetscCall(MatSetValue(A,II,II+n,-1.0,INSERT_VALUES));
     54:     if (j>0) PetscCall(MatSetValue(A,II,II-1,-1.0,INSERT_VALUES));
     55:     if (j<n-1) PetscCall(MatSetValue(A,II,II+1,-1.0,INSERT_VALUES));
     56:     PetscCall(MatSetValue(A,II,II,4.0,INSERT_VALUES));
     57:     PetscCall(MatSetValue(B,II,II,2.0,INSERT_VALUES));
     58:   }
     59:   if (Istart==0) {
     60:     PetscCall(MatSetValue(B,0,0,6.0,INSERT_VALUES));
     61:     PetscCall(MatSetValue(B,0,1,-1.0,INSERT_VALUES));
     62:     PetscCall(MatSetValue(B,1,0,-1.0,INSERT_VALUES));
     63:     PetscCall(MatSetValue(B,1,1,1.0,INSERT_VALUES));
     64:   }

     66:   PetscCall(MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY));
     67:   PetscCall(MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY));
     68:   PetscCall(MatAssemblyBegin(B,MAT_FINAL_ASSEMBLY));
     69:   PetscCall(MatAssemblyEnd(B,MAT_FINAL_ASSEMBLY));

     71:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     72:                 Create the eigensolver and set various options
     73:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

     75:   PetscCall(EPSCreate(PETSC_COMM_WORLD,&eps));
     76:   PetscCall(EPSSetOperators(eps,A,B));
     77:   PetscCall(EPSSetProblemType(eps,EPS_GHEP));
     78:   PetscCall(EPSSetType(eps,EPSBLOPEX));

     80:   /*
     81:      Set several options
     82:   */
     83:   PetscCall(EPSSetWhichEigenpairs(eps,EPS_SMALLEST_REAL));
     84:   PetscCall(EPSGetST(eps,&st));
     85:   PetscCall(STSetType(st,STPRECOND));
     86:   PetscCall(STGetKSP(st,&ksp));
     87:   PetscCall(KSPGetPC(ksp,&pc));
     88:   PetscCall(KSPSetType(ksp,KSPPREONLY));
     89:   PetscCall(PCSetType(pc,PCICC));

     91:   PetscCall(EPSBLOPEXSetBlockSize(eps,4));
     92:   PetscCall(EPSSetFromOptions(eps));

     94:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     95:            Compute all eigenvalues in interval and display info
     96:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

     98:   PetscCall(EPSSolve(eps));
     99:   PetscCall(EPSBLOPEXGetBlockSize(eps,&bs));
    100:   PetscCall(PetscPrintf(PETSC_COMM_WORLD," BLOPEX: using block size %" PetscInt_FMT "\n",bs));

    102:   PetscCall(EPSErrorView(eps,EPS_ERROR_ABSOLUTE,NULL));

    104:   PetscCall(EPSDestroy(&eps));
    105:   PetscCall(MatDestroy(&A));
    106:   PetscCall(MatDestroy(&B));
    107:   PetscCall(SlepcFinalize());
    108:   return 0;
    109: }

    111: /*TEST

    113:    build:
    114:       requires: blopex

    116:    test:
    117:       suffix: 1
    118:       args: -eps_nev 8 -eps_view
    119:       requires: blopex
    120:       filter: grep -v tolerance | sed -e "s/hermitian/symmetric/"

    122: TEST*/