Date: 2015-09-03T15:05:50+00:00

Actual source code: sleeper.c
slepc-3.6.1 2015-09-03
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      1: /*
      2:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      3:    SLEPc - Scalable Library for Eigenvalue Problem Computations
      4:    Copyright (c) 2002-2015, 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 sleeper problem is a proportionally damped QEP describing the
     30:    oscillations of a rail track resting on sleepers.
     31: */

     33: static char help[] = "NLEVP problem: sleeper.\n\n"
     34:   "The command line options are:\n"
     35:   "  -n <n>, where <n> = dimension of the matrices.\n\n";

     37: #include <slepcpep.h>

     41: int main(int argc,char **argv)
     42: {
     43:   Mat            M,C,K,A[3];      /* problem matrices */
     44:   PEP            pep;             /* polynomial eigenproblem solver context */
     45:   PetscInt       n=10,Istart,Iend,i;
     46:   PetscBool      terse;

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

     51:   PetscOptionsGetInt(NULL,"-n",&n,NULL);
     52:   PetscPrintf(PETSC_COMM_WORLD,"\nRailtrack resting on sleepers, n=%D\n\n",n);

     54:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     55:      Compute the matrices that define the eigensystem, (k^2*M+k*C+K)x=0
     56:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

     58:   /* K is a pentadiagonal */
     59:   MatCreate(PETSC_COMM_WORLD,&K);
     60:   MatSetSizes(K,PETSC_DECIDE,PETSC_DECIDE,n,n);
     61:   MatSetFromOptions(K);
     62:   MatSetUp(K);
     63:
     64:   MatGetOwnershipRange(K,&Istart,&Iend);
     65:   for (i=Istart;i<Iend;i++) {
     66:     if (i==0) {
     67:       MatSetValue(K,i,n-1,-3.0,INSERT_VALUES);
     68:       MatSetValue(K,i,n-2,1.0,INSERT_VALUES);
     69:     }
     70:     if (i==1) { MatSetValue(K,i,n-1,1.0,INSERT_VALUES); }
     71:     if (i>0) { MatSetValue(K,i,i-1,-3.0,INSERT_VALUES); }
     72:     if (i>1) { MatSetValue(K,i,i-2,1.0,INSERT_VALUES); }
     73:     MatSetValue(K,i,i,5.0,INSERT_VALUES);
     74:     if (i==n-1) {
     75:       MatSetValue(K,i,0,-3.0,INSERT_VALUES);
     76:       MatSetValue(K,i,1,1.0,INSERT_VALUES);
     77:     }
     78:     if (i==n-2) { MatSetValue(K,i,0,1.0,INSERT_VALUES); }
     79:     if (i<n-1) { MatSetValue(K,i,i+1,-3.0,INSERT_VALUES); }
     80:     if (i<n-2) { MatSetValue(K,i,i+2,1.0,INSERT_VALUES); }
     81:   }

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

     86:   /* C is a circulant matrix */
     87:   MatCreate(PETSC_COMM_WORLD,&C);
     88:   MatSetSizes(C,PETSC_DECIDE,PETSC_DECIDE,n,n);
     89:   MatSetFromOptions(C);
     90:   MatSetUp(C);
     91:
     92:   MatGetOwnershipRange(C,&Istart,&Iend);
     93:   for (i=Istart;i<Iend;i++) {
     94:     if (i==0) {
     95:       MatSetValue(C,i,n-1,-4.0,INSERT_VALUES);
     96:       MatSetValue(C,i,n-2,1.0,INSERT_VALUES);
     97:     }
     98:     if (i==1) { MatSetValue(C,i,n-1,1.0,INSERT_VALUES); }
     99:     if (i>0) { MatSetValue(C,i,i-1,-4.0,INSERT_VALUES); }
    100:     if (i>1) { MatSetValue(C,i,i-2,1.0,INSERT_VALUES); }
    101:     MatSetValue(C,i,i,7.0,INSERT_VALUES);
    102:     if (i==n-1) {
    103:       MatSetValue(C,i,0,-4.0,INSERT_VALUES);
    104:       MatSetValue(C,i,1,1.0,INSERT_VALUES);
    105:     }
    106:     if (i==n-2) { MatSetValue(C,i,0,1.0,INSERT_VALUES); }
    107:     if (i<n-1) { MatSetValue(C,i,i+1,-4.0,INSERT_VALUES); }
    108:     if (i<n-2) { MatSetValue(C,i,i+2,1.0,INSERT_VALUES); }
    109:   }

    111:   MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY);
    112:   MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY);
    113:
    114:   /* M is the identity matrix */
    115:   MatCreate(PETSC_COMM_WORLD,&M);
    116:   MatSetSizes(M,PETSC_DECIDE,PETSC_DECIDE,n,n);
    117:   MatSetFromOptions(M);
    118:   MatSetUp(M);
    119:   MatGetOwnershipRange(M,&Istart,&Iend);
    120:   for (i=Istart;i<Iend;i++) {
    121:     MatSetValue(M,i,i,1.0,INSERT_VALUES);
    122:   }
    123:   MatAssemblyBegin(M,MAT_FINAL_ASSEMBLY);
    124:   MatAssemblyEnd(M,MAT_FINAL_ASSEMBLY);

    126:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    127:                 Create the eigensolver and solve the problem
    128:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

    130:   PEPCreate(PETSC_COMM_WORLD,&pep);
    131:   A[0] = K; A[1] = C; A[2] = M;
    132:   PEPSetOperators(pep,3,A);
    133:   PEPSetFromOptions(pep);
    134:   PEPSolve(pep);

    136:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    137:                     Display solution and clean up
    138:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
    139:
    140:   /* show detailed info unless -terse option is given by user */
    141:   PetscOptionsHasName(NULL,"-terse",&terse);
    142:   if (terse) {
    143:     PEPErrorView(pep,PEP_ERROR_BACKWARD,NULL);
    144:   } else {
    145:     PetscViewerPushFormat(PETSC_VIEWER_STDOUT_WORLD,PETSC_VIEWER_ASCII_INFO_DETAIL);
    146:     PEPReasonView(pep,PETSC_VIEWER_STDOUT_WORLD);
    147:     PEPErrorView(pep,PEP_ERROR_BACKWARD,PETSC_VIEWER_STDOUT_WORLD);
    148:     PetscViewerPopFormat(PETSC_VIEWER_STDOUT_WORLD);
    149:   }
    150:   PEPDestroy(&pep);
    151:   MatDestroy(&M);
    152:   MatDestroy(&C);
    153:   MatDestroy(&K);
    154:   SlepcFinalize();
    155:   return 0;
    156: }