Date: 2017-05-17T08:27:08+00:00

Actual source code: acoustic_wave_2d.c
slepc-3.7.4 2017-05-17
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      1: /*
      2:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      3:    SLEPc - Scalable Library for Eigenvalue Problem Computations
      4:    Copyright (c) 2002-2016, 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: */
     21: /*
     22:    This example implements one of the problems found at
     23:        NLEVP: A Collection of Nonlinear Eigenvalue Problems,
     24:        The University of Manchester.
     25:    The details of the collection can be found at:
     26:        [1] T. Betcke et al., "NLEVP: A Collection of Nonlinear Eigenvalue
     27:            Problems", ACM Trans. Math. Software 39(2), Article 7, 2013.

     29:    The acoustic_wave_2d problem is a 2-D version of acoustic_wave_1d, also
     30:    scaled for real arithmetic.
     31: */

     33: static char help[] = "Quadratic eigenproblem from an acoustics application (2-D).\n\n"
     34:   "The command line options are:\n"
     35:   "  -m <m>, where <m> = grid size, the matrices have dimension m*(m-1).\n"
     36:   "  -z <z>, where <z> = impedance (default 1.0).\n\n";

     38: #include <slepcpep.h>

     42: int main(int argc,char **argv)
     43: {
     44:   Mat            M,C,K,A[3];      /* problem matrices */
     45:   PEP            pep;             /* polynomial eigenproblem solver context */
     46:   PetscInt       m=6,n,II,Istart,Iend,i,j;
     47:   PetscScalar    z=1.0;
     48:   PetscReal      h;
     49:   char           str[50];
     50:   PetscBool      terse;

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

     55:   PetscOptionsGetInt(NULL,NULL,"-m",&m,NULL);
     56:   if (m<2) SETERRQ(PETSC_COMM_SELF,1,"m must be at least 2");
     57:   PetscOptionsGetScalar(NULL,NULL,"-z",&z,NULL);
     58:   h = 1.0/m;
     59:   n = m*(m-1);
     60:   SlepcSNPrintfScalar(str,50,z,PETSC_FALSE);
     61:   PetscPrintf(PETSC_COMM_WORLD,"\nAcoustic wave 2-D, n=%D (m=%D), z=%s\n\n",n,m,str);

     63:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     64:      Compute the matrices that define the eigensystem, (k^2*M+k*C+K)x=0
     65:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

     67:   /* K has a pattern similar to the 2D Laplacian */
     68:   MatCreate(PETSC_COMM_WORLD,&K);
     69:   MatSetSizes(K,PETSC_DECIDE,PETSC_DECIDE,n,n);
     70:   MatSetFromOptions(K);
     71:   MatSetUp(K);
     72:
     73:   MatGetOwnershipRange(K,&Istart,&Iend);
     74:   for (II=Istart;II<Iend;II++) {
     75:     i = II/m; j = II-i*m;
     76:     if (i>0) { MatSetValue(K,II,II-m,(j==m-1)?-0.5:-1.0,INSERT_VALUES); }
     77:     if (i<m-2) { MatSetValue(K,II,II+m,(j==m-1)?-0.5:-1.0,INSERT_VALUES); }
     78:     if (j>0) { MatSetValue(K,II,II-1,-1.0,INSERT_VALUES); }
     79:     if (j<m-1) { MatSetValue(K,II,II+1,-1.0,INSERT_VALUES); }
     80:     MatSetValue(K,II,II,(j==m-1)?2.0:4.0,INSERT_VALUES);
     81:   }

     83:   MatAssemblyBegin(K,MAT_FINAL_ASSEMBLY);
     84:   MatAssemblyEnd(K,MAT_FINAL_ASSEMBLY);

     86:   /* C is the zero matrix except for a few nonzero elements on the diagonal */
     87:   MatCreate(PETSC_COMM_WORLD,&C);
     88:   MatSetSizes(C,PETSC_DECIDE,PETSC_DECIDE,n,n);
     89:   MatSetFromOptions(C);
     90:   MatSetUp(C);

     92:   MatGetOwnershipRange(C,&Istart,&Iend);
     93:   for (i=Istart;i<Iend;i++) {
     94:     if (i%m==m-1) {
     95:       MatSetValue(C,i,i,-2*PETSC_PI*h/z,INSERT_VALUES);
     96:     }
     97:   }
     98:   MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY);
     99:   MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY);
    100:
    101:   /* M is a diagonal matrix */
    102:   MatCreate(PETSC_COMM_WORLD,&M);
    103:   MatSetSizes(M,PETSC_DECIDE,PETSC_DECIDE,n,n);
    104:   MatSetFromOptions(M);
    105:   MatSetUp(M);

    107:   MatGetOwnershipRange(M,&Istart,&Iend);
    108:   for (i=Istart;i<Iend;i++) {
    109:     if (i%m==m-1) {
    110:       MatSetValue(M,i,i,2*PETSC_PI*PETSC_PI*h*h,INSERT_VALUES);
    111:     } else {
    112:       MatSetValue(M,i,i,4*PETSC_PI*PETSC_PI*h*h,INSERT_VALUES);
    113:     }
    114:   }
    115:   MatAssemblyBegin(M,MAT_FINAL_ASSEMBLY);
    116:   MatAssemblyEnd(M,MAT_FINAL_ASSEMBLY);
    117:
    118:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    119:                 Create the eigensolver and solve the problem
    120:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

    122:   PEPCreate(PETSC_COMM_WORLD,&pep);
    123:   A[0] = K; A[1] = C; A[2] = M;
    124:   PEPSetOperators(pep,3,A);
    125:   PEPSetFromOptions(pep);
    126:   PEPSolve(pep);

    128:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    129:                     Display solution and clean up
    130:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
    131:
    132:   /* show detailed info unless -terse option is given by user */
    133:   PetscOptionsHasName(NULL,NULL,"-terse",&terse);
    134:   if (terse) {
    135:     PEPErrorView(pep,PEP_ERROR_BACKWARD,NULL);
    136:   } else {
    137:     PetscViewerPushFormat(PETSC_VIEWER_STDOUT_WORLD,PETSC_VIEWER_ASCII_INFO_DETAIL);
    138:     PEPReasonView(pep,PETSC_VIEWER_STDOUT_WORLD);
    139:     PEPErrorView(pep,PEP_ERROR_BACKWARD,PETSC_VIEWER_STDOUT_WORLD);
    140:     PetscViewerPopFormat(PETSC_VIEWER_STDOUT_WORLD);
    141:   }
    142:   PEPDestroy(&pep);
    143:   MatDestroy(&M);
    144:   MatDestroy(&C);
    145:   MatDestroy(&K);
    146:   SlepcFinalize();
    147:   return ierr;
    148: }