Date: 2013-09-02T10:07:36+00:00

Actual source code: ex16.c

      1: /*
      2:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      3:    SLEPc - Scalable Library for Eigenvalue Problem Computations
      4:    Copyright (c) 2002-2013, Universitat Politecnica de Valencia, Spain

      6:    This file is part of SLEPc.

      8:    SLEPc is free software: you can redistribute it and/or modify it under  the
      9:    terms of version 3 of the GNU Lesser General Public License as published by
     10:    the Free Software Foundation.

     12:    SLEPc  is  distributed in the hope that it will be useful, but WITHOUT  ANY
     13:    WARRANTY;  without even the implied warranty of MERCHANTABILITY or  FITNESS
     14:    FOR  A  PARTICULAR PURPOSE. See the GNU Lesser General Public  License  for
     15:    more details.

     17:    You  should have received a copy of the GNU Lesser General  Public  License
     18:    along with SLEPc. If not, see <http://www.gnu.org/licenses/>.
     19:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     20: */

     22: static char help[] = "Quadratic eigenproblem for testing the QEP object.\n\n"
     23:   "The command line options are:\n"
     24:   "  -n <n>, where <n> = number of grid subdivisions in x dimension.\n"
     25:   "  -m <m>, where <m> = number of grid subdivisions in y dimension.\n\n";

     27: #include <slepcqep.h>

     31: int main(int argc,char **argv)
     32: {
     33:   Mat            M,C,K;           /* problem matrices */
     34:   QEP            qep;             /* quadratic eigenproblem solver context */
     35:   QEPType        type;
     36:   PetscInt       N,n=10,m,Istart,Iend,II,nev,i,j;
     37:   PetscBool      flag;

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

     42:   PetscOptionsGetInt(NULL,"-n",&n,NULL);
     43:   PetscOptionsGetInt(NULL,"-m",&m,&flag);
     44:   if (!flag) m=n;
     45:   N = n*m;
     46:   PetscPrintf(PETSC_COMM_WORLD,"\nQuadratic Eigenproblem, N=%D (%Dx%D grid)\n\n",N,n,m);

     48:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     49:      Compute the matrices that define the eigensystem, (k^2*M+k*C+K)x=0
     50:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

     52:   /* K is the 2-D Laplacian */
     53:   MatCreate(PETSC_COMM_WORLD,&K);
     54:   MatSetSizes(K,PETSC_DECIDE,PETSC_DECIDE,N,N);
     55:   MatSetFromOptions(K);
     56:   MatSetUp(K);

     58:   MatGetOwnershipRange(K,&Istart,&Iend);
     59:   for (II=Istart;II<Iend;II++) {
     60:     i = II/n; j = II-i*n;
     61:     if (i>0) { MatSetValue(K,II,II-n,-1.0,INSERT_VALUES); }
     62:     if (i<m-1) { MatSetValue(K,II,II+n,-1.0,INSERT_VALUES); }
     63:     if (j>0) { MatSetValue(K,II,II-1,-1.0,INSERT_VALUES); }
     64:     if (j<n-1) { MatSetValue(K,II,II+1,-1.0,INSERT_VALUES); }
     65:     MatSetValue(K,II,II,4.0,INSERT_VALUES);
     66:   }

     68:   MatAssemblyBegin(K,MAT_FINAL_ASSEMBLY);
     69:   MatAssemblyEnd(K,MAT_FINAL_ASSEMBLY);

     71:   /* C is the zero matrix */
     72:   MatCreate(PETSC_COMM_WORLD,&C);
     73:   MatSetSizes(C,PETSC_DECIDE,PETSC_DECIDE,N,N);
     74:   MatSetFromOptions(C);
     75:   MatSetUp(C);
     76:   MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY);
     77:   MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY);

     79:   /* M is the identity matrix */
     80:   MatCreate(PETSC_COMM_WORLD,&M);
     81:   MatSetSizes(M,PETSC_DECIDE,PETSC_DECIDE,N,N);
     82:   MatSetFromOptions(M);
     83:   MatSetUp(M);
     84:   MatAssemblyBegin(M,MAT_FINAL_ASSEMBLY);
     85:   MatAssemblyEnd(M,MAT_FINAL_ASSEMBLY);
     86:   MatShift(M,1.0);

     88:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     89:                 Create the eigensolver and set various options
     90:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

     92:   /*
     93:      Create eigensolver context
     94:   */
     95:   QEPCreate(PETSC_COMM_WORLD,&qep);

     97:   /*
     98:      Set matrices and problem type
     99:   */
    100:   QEPSetOperators(qep,M,C,K);
    101:   QEPSetProblemType(qep,QEP_HERMITIAN);

    103:   /*
    104:      Set solver parameters at runtime
    105:   */
    106:   QEPSetFromOptions(qep);

    108:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    109:                       Solve the eigensystem
    110:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

    112:   QEPSolve(qep);

    114:   /*
    115:      Optional: Get some information from the solver and display it
    116:   */
    117:   QEPGetType(qep,&type);
    118:   PetscPrintf(PETSC_COMM_WORLD," Solution method: %s\n\n",type);
    119:   QEPGetDimensions(qep,&nev,NULL,NULL);
    120:   PetscPrintf(PETSC_COMM_WORLD," Number of requested eigenvalues: %D\n",nev);

    122:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    123:                     Display solution and clean up
    124:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

    126:   QEPPrintSolution(qep,NULL);
    127:   QEPDestroy(&qep);
    128:   MatDestroy(&M);
    129:   MatDestroy(&C);
    130:   MatDestroy(&K);
    131:   SlepcFinalize();
    132:   return 0;
    133: }