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

Actual source code: acoustic_wave_2d.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_2d problem is a 2-D version of acoustic_wave_1d, also
     19:    scaled for real arithmetic.
     20: */

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

     27: #include <slepcpep.h>

     29: int main(int argc,char **argv)
     30: {
     31:   Mat            M,C,K,A[3];      /* problem matrices */
     32:   PEP            pep;             /* polynomial eigenproblem solver context */
     33:   PetscInt       m=6,n,II,Istart,Iend,i,j;
     34:   PetscScalar    z=1.0;
     35:   PetscReal      h;
     36:   char           str[50];
     37:   PetscBool      terse;

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

     42:   PetscOptionsGetInt(NULL,NULL,"-m",&m,NULL);
     44:   PetscOptionsGetScalar(NULL,NULL,"-z",&z,NULL);
     45:   h = 1.0/m;
     46:   n = m*(m-1);
     47:   SlepcSNPrintfScalar(str,sizeof(str),z,PETSC_FALSE);
     48:   PetscPrintf(PETSC_COMM_WORLD,"\nAcoustic wave 2-D, n=%" PetscInt_FMT " (m=%" PetscInt_FMT "), z=%s\n\n",n,m,str);

     50:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     51:      Compute the matrices that define the eigensystem, (k^2*M+k*C+K)x=0
     52:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

     54:   /* K has a pattern similar to the 2D Laplacian */
     55:   MatCreate(PETSC_COMM_WORLD,&K);
     56:   MatSetSizes(K,PETSC_DECIDE,PETSC_DECIDE,n,n);
     57:   MatSetFromOptions(K);
     58:   MatSetUp(K);

     60:   MatGetOwnershipRange(K,&Istart,&Iend);
     61:   for (II=Istart;II<Iend;II++) {
     62:     i = II/m; j = II-i*m;
     63:     if (i>0) MatSetValue(K,II,II-m,(j==m-1)?-0.5:-1.0,INSERT_VALUES);
     64:     if (i<m-2) MatSetValue(K,II,II+m,(j==m-1)?-0.5:-1.0,INSERT_VALUES);
     65:     if (j>0) MatSetValue(K,II,II-1,-1.0,INSERT_VALUES);
     66:     if (j<m-1) MatSetValue(K,II,II+1,-1.0,INSERT_VALUES);
     67:     MatSetValue(K,II,II,(j==m-1)?2.0:4.0,INSERT_VALUES);
     68:   }

     70:   MatAssemblyBegin(K,MAT_FINAL_ASSEMBLY);
     71:   MatAssemblyEnd(K,MAT_FINAL_ASSEMBLY);

     73:   /* C is the zero matrix except for a few nonzero elements on the diagonal */
     74:   MatCreate(PETSC_COMM_WORLD,&C);
     75:   MatSetSizes(C,PETSC_DECIDE,PETSC_DECIDE,n,n);
     76:   MatSetFromOptions(C);
     77:   MatSetUp(C);

     79:   MatGetOwnershipRange(C,&Istart,&Iend);
     80:   for (i=Istart;i<Iend;i++) {
     81:     if (i%m==m-1) MatSetValue(C,i,i,-2*PETSC_PI*h/z,INSERT_VALUES);
     82:   }
     83:   MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY);
     84:   MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY);

     86:   /* M is a diagonal matrix */
     87:   MatCreate(PETSC_COMM_WORLD,&M);
     88:   MatSetSizes(M,PETSC_DECIDE,PETSC_DECIDE,n,n);
     89:   MatSetFromOptions(M);
     90:   MatSetUp(M);

     92:   MatGetOwnershipRange(M,&Istart,&Iend);
     93:   for (i=Istart;i<Iend;i++) {
     94:     if (i%m==m-1) MatSetValue(M,i,i,2*PETSC_PI*PETSC_PI*h*h,INSERT_VALUES);
     95:     else MatSetValue(M,i,i,4*PETSC_PI*PETSC_PI*h*h,INSERT_VALUES);
     96:   }
     97:   MatAssemblyBegin(M,MAT_FINAL_ASSEMBLY);
     98:   MatAssemblyEnd(M,MAT_FINAL_ASSEMBLY);

    100:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    101:                 Create the eigensolver and solve the problem
    102:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

    104:   PEPCreate(PETSC_COMM_WORLD,&pep);
    105:   A[0] = K; A[1] = C; A[2] = M;
    106:   PEPSetOperators(pep,3,A);
    107:   PEPSetFromOptions(pep);
    108:   PEPSolve(pep);

    110:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    111:                     Display solution and clean up
    112:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

    114:   /* show detailed info unless -terse option is given by user */
    115:   PetscOptionsHasName(NULL,NULL,"-terse",&terse);
    116:   if (terse) PEPErrorView(pep,PEP_ERROR_BACKWARD,NULL);
    117:   else {
    118:     PetscViewerPushFormat(PETSC_VIEWER_STDOUT_WORLD,PETSC_VIEWER_ASCII_INFO_DETAIL);
    119:     PEPConvergedReasonView(pep,PETSC_VIEWER_STDOUT_WORLD);
    120:     PEPErrorView(pep,PEP_ERROR_BACKWARD,PETSC_VIEWER_STDOUT_WORLD);
    121:     PetscViewerPopFormat(PETSC_VIEWER_STDOUT_WORLD);
    122:   }
    123:   PEPDestroy(&pep);
    124:   MatDestroy(&M);
    125:   MatDestroy(&C);
    126:   MatDestroy(&K);
    127:   SlepcFinalize();
    128:   return 0;
    129: }

    131: /*TEST

    133:    testset:
    134:       args: -pep_nev 2 -pep_ncv 18 -terse
    135:       output_file: output/acoustic_wave_2d_1.out
    136:       filter: sed -e "s/2.60936i/2.60937i/g" | sed -e "s/2.60938i/2.60937i/g"
    137:       test:
    138:          suffix: 1
    139:          args: -pep_type {{qarnoldi linear}}
    140:       test:
    141:          suffix: 1_toar
    142:          args: -pep_type toar -pep_toar_locking 0

    144:    testset:
    145:       args: -pep_nev 2 -pep_ncv 18 -pep_type stoar -pep_hermitian -pep_scale scalar -st_type sinvert -terse
    146:       output_file: output/acoustic_wave_2d_2.out
    147:       test:
    148:          suffix: 2
    149:       test:
    150:          suffix: 2_lin_b
    151:          args: -pep_stoar_linearization 0,1
    152:       test:
    153:          suffix: 2_lin_ab
    154:          args: -pep_stoar_linearization 0.1,0.9

    156: TEST*/