Date: 2022-11-02T11:47:28+00:00

Actual source code: acoustic_wave_1d.c
slepc-3.18.1 2022-11-02
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      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: */
     10: /*
     11:    This example implements one of the problems found at
     12:        NLEVP: A Collection of Nonlinear Eigenvalue Problems,
     13:        The University of Manchester.
     14:    The details of the collection can be found at:
     15:        [1] T. Betcke et al., "NLEVP: A Collection of Nonlinear Eigenvalue
     16:            Problems", ACM Trans. Math. Software 39(2), Article 7, 2013.

     18:    The acoustic_wave_1d problem is a QEP from an acoustics application.
     19:    Here we solve it with the eigenvalue scaled by the imaginary unit, to be
     20:    able to use real arithmetic, so the computed eigenvalues should be scaled
     21:    back.
     22: */

     24: static char help[] = "Quadratic eigenproblem from an acoustics application (1-D).\n\n"
     25:   "The command line options are:\n"
     26:   "  -n <n>, where <n> = dimension of the matrices.\n"
     27:   "  -z <z>, where <z> = impedance (default 1.0).\n\n";

     29: #include <slepcpep.h>

     31: int main(int argc,char **argv)
     32: {
     33:   Mat            M,C,K,A[3];      /* problem matrices */
     34:   PEP            pep;             /* polynomial eigenproblem solver context */
     35:   PetscInt       n=10,Istart,Iend,i;
     36:   PetscScalar    z=1.0;
     37:   char           str[50];
     38:   PetscBool      terse;

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

     43:   PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL);
     44:   PetscOptionsGetScalar(NULL,NULL,"-z",&z,NULL);
     45:   SlepcSNPrintfScalar(str,sizeof(str),z,PETSC_FALSE);
     46:   PetscPrintf(PETSC_COMM_WORLD,"\nAcoustic wave 1-D, n=%" PetscInt_FMT " z=%s\n\n",n,str);

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

     52:   /* K is a tridiagonal */
     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 (i=Istart;i<Iend;i++) {
     60:     if (i>0) MatSetValue(K,i,i-1,-1.0*n,INSERT_VALUES);
     61:     if (i<n-1) {
     62:       MatSetValue(K,i,i,2.0*n,INSERT_VALUES);
     63:       MatSetValue(K,i,i+1,-1.0*n,INSERT_VALUES);
     64:     } else MatSetValue(K,i,i,1.0*n,INSERT_VALUES);
     65:   }

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

     70:   /* C is the zero matrix but one element*/
     71:   MatCreate(PETSC_COMM_WORLD,&C);
     72:   MatSetSizes(C,PETSC_DECIDE,PETSC_DECIDE,n,n);
     73:   MatSetFromOptions(C);
     74:   MatSetUp(C);

     76:   MatGetOwnershipRange(C,&Istart,&Iend);
     77:   if (n-1>=Istart && n-1<Iend) MatSetValue(C,n-1,n-1,-2*PETSC_PI/z,INSERT_VALUES);
     78:   MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY);
     79:   MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY);

     81:   /* M is a diagonal matrix */
     82:   MatCreate(PETSC_COMM_WORLD,&M);
     83:   MatSetSizes(M,PETSC_DECIDE,PETSC_DECIDE,n,n);
     84:   MatSetFromOptions(M);
     85:   MatSetUp(M);

     87:   MatGetOwnershipRange(M,&Istart,&Iend);
     88:   for (i=Istart;i<Iend;i++) {
     89:     if (i<n-1) MatSetValue(M,i,i,4*PETSC_PI*PETSC_PI/n,INSERT_VALUES);
     90:     else MatSetValue(M,i,i,2*PETSC_PI*PETSC_PI/n,INSERT_VALUES);
     91:   }
     92:   MatAssemblyBegin(M,MAT_FINAL_ASSEMBLY);
     93:   MatAssemblyEnd(M,MAT_FINAL_ASSEMBLY);

     95:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     96:                 Create the eigensolver and solve the problem
     97:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

     99:   PEPCreate(PETSC_COMM_WORLD,&pep);
    100:   A[0] = K; A[1] = C; A[2] = M;
    101:   PEPSetOperators(pep,3,A);
    102:   PEPSetFromOptions(pep);
    103:   PEPSolve(pep);

    105:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    106:                     Display solution and clean up
    107:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

    109:   /* show detailed info unless -terse option is given by user */
    110:   PetscOptionsHasName(NULL,NULL,"-terse",&terse);
    111:   if (terse) PEPErrorView(pep,PEP_ERROR_BACKWARD,NULL);
    112:   else {
    113:     PetscViewerPushFormat(PETSC_VIEWER_STDOUT_WORLD,PETSC_VIEWER_ASCII_INFO_DETAIL);
    114:     PEPConvergedReasonView(pep,PETSC_VIEWER_STDOUT_WORLD);
    115:     PEPErrorView(pep,PEP_ERROR_BACKWARD,PETSC_VIEWER_STDOUT_WORLD);
    116:     PetscViewerPopFormat(PETSC_VIEWER_STDOUT_WORLD);
    117:   }
    118:   PEPDestroy(&pep);
    119:   MatDestroy(&M);
    120:   MatDestroy(&C);
    121:   MatDestroy(&K);
    122:   SlepcFinalize();
    123:   return 0;
    124: }

    126: /*TEST

    128:    testset:
    129:       args: -pep_nev 4 -pep_tol 1e-7 -n 24 -terse
    130:       output_file: output/acoustic_wave_1d_1.out
    131:       requires: !single
    132:       test:
    133:          suffix: 1
    134:          args: -st_type sinvert -st_transform -pep_type {{toar qarnoldi linear}}
    135:       test:
    136:          suffix: 1_stoar
    137:          args: -st_type sinvert -st_transform -pep_type stoar -pep_hermitian -pep_stoar_locking 0 -pep_stoar_nev 11 -pep_ncv 10
    138:       test:
    139:          suffix: 2
    140:          args: -st_type sinvert -st_transform -pep_type toar -pep_extract {{none norm residual}}
    141:       test:
    142:          suffix: 3
    143:          args: -st_type sinvert -pep_type linear -pep_extract {{none norm residual}}
    144:       test:
    145:          suffix: 4
    146:          args: -pep_type jd

    148: TEST*/