Date: 2021-02-01T14:42:14+00:00

Actual source code: acoustic_wave_2d.c
slepc-3.14.2 2021-02-01
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      1: /*
      2:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      3:    SLEPc - Scalable Library for Eigenvalue Problem Computations
      4:    Copyright (c) 2002-2020, 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);if (ierr) return ierr;

     42:   PetscOptionsGetInt(NULL,NULL,"-m",&m,NULL);
     43:   if (m<2) SETERRQ(PETSC_COMM_WORLD,1,"m must be at least 2");
     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=%D (m=%D), 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) {
     82:       MatSetValue(C,i,i,-2*PETSC_PI*h/z,INSERT_VALUES);
     83:     }
     84:   }
     85:   MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY);
     86:   MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY);

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

     94:   MatGetOwnershipRange(M,&Istart,&Iend);
     95:   for (i=Istart;i<Iend;i++) {
     96:     if (i%m==m-1) {
     97:       MatSetValue(M,i,i,2*PETSC_PI*PETSC_PI*h*h,INSERT_VALUES);
     98:     } else {
     99:       MatSetValue(M,i,i,4*PETSC_PI*PETSC_PI*h*h,INSERT_VALUES);
    100:     }
    101:   }
    102:   MatAssemblyBegin(M,MAT_FINAL_ASSEMBLY);
    103:   MatAssemblyEnd(M,MAT_FINAL_ASSEMBLY);

    105:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    106:                 Create the eigensolver and solve the problem
    107:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

    109:   PEPCreate(PETSC_COMM_WORLD,&pep);
    110:   A[0] = K; A[1] = C; A[2] = M;
    111:   PEPSetOperators(pep,3,A);
    112:   PEPSetFromOptions(pep);
    113:   PEPSolve(pep);

    115:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    116:                     Display solution and clean up
    117:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

    119:   /* show detailed info unless -terse option is given by user */
    120:   PetscOptionsHasName(NULL,NULL,"-terse",&terse);
    121:   if (terse) {
    122:     PEPErrorView(pep,PEP_ERROR_BACKWARD,NULL);
    123:   } else {
    124:     PetscViewerPushFormat(PETSC_VIEWER_STDOUT_WORLD,PETSC_VIEWER_ASCII_INFO_DETAIL);
    125:     PEPConvergedReasonView(pep,PETSC_VIEWER_STDOUT_WORLD);
    126:     PEPErrorView(pep,PEP_ERROR_BACKWARD,PETSC_VIEWER_STDOUT_WORLD);
    127:     PetscViewerPopFormat(PETSC_VIEWER_STDOUT_WORLD);
    128:   }
    129:   PEPDestroy(&pep);
    130:   MatDestroy(&M);
    131:   MatDestroy(&C);
    132:   MatDestroy(&K);
    133:   SlepcFinalize();
    134:   return ierr;
    135: }

    137: /*TEST

    139:    testset:
    140:       args: -pep_nev 2 -pep_ncv 18 -terse
    141:       output_file: output/acoustic_wave_2d_1.out
    142:       filter: sed -e "s/2.60936i/2.60937i/g"
    143:       test:
    144:          suffix: 1
    145:          args: -pep_type {{qarnoldi linear}}
    146:       test:
    147:          suffix: 1_toar
    148:          args: -pep_type toar -pep_toar_locking 0

    150:    test:
    151:       suffix: 2
    152:       args: -pep_nev 2 -pep_ncv 18 -pep_type stoar -pep_hermitian -pep_scale scalar -st_type sinvert -terse

    154: TEST*/