Actual source code: spring.c
slepc-3.10.1 2018-10-23
Report Typos and Errors

      1: /*
      2:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      3:    SLEPc - Scalable Library for Eigenvalue Problem Computations
      4:    Copyright (c) 2002-2018, 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 spring problem is a QEP from the finite element model of a damped
     19:    mass-spring system. This implementation supports only scalar parameters,
     20:    that is all masses, dampers and springs have the same constants.
     21:    Furthermore, this implementation does not consider different constants
     22:    for dampers and springs connecting adjacent masses or masses to the ground.
     23: */

     25: static char help[] = "FEM model of a damped mass-spring system.\n\n"
     26:   "The command line options are:\n"
     27:   "  -n <n> ... dimension of the matrices.\n"
     28:   "  -mu <value> ... mass (default 1).\n"
     29:   "  -tau <value> ... damping constant of the dampers (default 10).\n"
     30:   "  -kappa <value> ... damping constant of the springs (default 5).\n\n";

     32: #include <slepcpep.h>

     34: int main(int argc,char **argv)
     35: {
     36:   Mat            M,C,K,A[3];      /* problem matrices */
     37:   PEP            pep;             /* polynomial eigenproblem solver context */
     38:   PetscInt       n=5,Istart,Iend,i;
     39:   PetscReal      mu=1,tau=10,kappa=5;
     40:   PetscBool      terse;

     43:   SlepcInitialize(&argc,&argv,(char*)0,help);if (ierr) return ierr;

     45:   PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL);
     46:   PetscOptionsGetReal(NULL,NULL,"-mu",&mu,NULL);
     47:   PetscOptionsGetReal(NULL,NULL,"-tau",&tau,NULL);
     48:   PetscOptionsGetReal(NULL,NULL,"-kappa",&kappa,NULL);
     49:   PetscPrintf(PETSC_COMM_WORLD,"\nDamped mass-spring system, n=%D mu=%g tau=%g kappa=%g\n\n",n,(double)mu,(double)tau,(double)kappa);

     51:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     52:      Compute the matrices that define the eigensystem, (k^2*M+k*C+K)x=0
     53:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

     55:   /* K is a tridiagonal */
     56:   MatCreate(PETSC_COMM_WORLD,&K);
     57:   MatSetSizes(K,PETSC_DECIDE,PETSC_DECIDE,n,n);
     58:   MatSetFromOptions(K);
     59:   MatSetUp(K);

     61:   MatGetOwnershipRange(K,&Istart,&Iend);
     62:   for (i=Istart;i<Iend;i++) {
     63:     if (i>0) {
     64:       MatSetValue(K,i,i-1,-kappa,INSERT_VALUES);
     65:     }
     66:     MatSetValue(K,i,i,kappa*3.0,INSERT_VALUES);
     67:     if (i<n-1) {
     68:       MatSetValue(K,i,i+1,-kappa,INSERT_VALUES);
     69:     }
     70:   }

     72:   MatAssemblyBegin(K,MAT_FINAL_ASSEMBLY);
     73:   MatAssemblyEnd(K,MAT_FINAL_ASSEMBLY);

     75:   /* C is a tridiagonal */
     76:   MatCreate(PETSC_COMM_WORLD,&C);
     77:   MatSetSizes(C,PETSC_DECIDE,PETSC_DECIDE,n,n);
     78:   MatSetFromOptions(C);
     79:   MatSetUp(C);

     81:   MatGetOwnershipRange(C,&Istart,&Iend);
     82:   for (i=Istart;i<Iend;i++) {
     83:     if (i>0) {
     84:       MatSetValue(C,i,i-1,-tau,INSERT_VALUES);
     85:     }
     86:     MatSetValue(C,i,i,tau*3.0,INSERT_VALUES);
     87:     if (i<n-1) {
     88:       MatSetValue(C,i,i+1,-tau,INSERT_VALUES);
     89:     }
     90:   }

     92:   MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY);
     93:   MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY);

     95:   /* M is a diagonal matrix */
     96:   MatCreate(PETSC_COMM_WORLD,&M);
     97:   MatSetSizes(M,PETSC_DECIDE,PETSC_DECIDE,n,n);
     98:   MatSetFromOptions(M);
     99:   MatSetUp(M);
    100:   MatGetOwnershipRange(M,&Istart,&Iend);
    101:   for (i=Istart;i<Iend;i++) {
    102:     MatSetValue(M,i,i,mu,INSERT_VALUES);
    103:   }
    104:   MatAssemblyBegin(M,MAT_FINAL_ASSEMBLY);
    105:   MatAssemblyEnd(M,MAT_FINAL_ASSEMBLY);

    107:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    108:                 Create the eigensolver and solve the problem
    109:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

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

    117:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    118:                     Display solution and clean up
    119:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

    121:   /* show detailed info unless -terse option is given by user */
    122:   PetscOptionsHasName(NULL,NULL,"-terse",&terse);
    123:   if (terse) {
    124:     PEPErrorView(pep,PEP_ERROR_BACKWARD,NULL);
    125:   } else {
    126:     PetscViewerPushFormat(PETSC_VIEWER_STDOUT_WORLD,PETSC_VIEWER_ASCII_INFO_DETAIL);
    127:     PEPReasonView(pep,PETSC_VIEWER_STDOUT_WORLD);
    128:     PEPErrorView(pep,PEP_ERROR_BACKWARD,PETSC_VIEWER_STDOUT_WORLD);
    129:     PetscViewerPopFormat(PETSC_VIEWER_STDOUT_WORLD);
    130:   }
    131:   PEPDestroy(&pep);
    132:   MatDestroy(&M);
    133:   MatDestroy(&C);
    134:   MatDestroy(&K);
    135:   SlepcFinalize();
    136:   return ierr;
    137: }

    139: /*TEST

    141:    testset:
    142:       args: -pep_nev 4 -n 24 -pep_ncv 18 -pep_target -.5 -st_type sinvert -pep_scale diagonal -terse
    143:       requires: !single
    144:       output_file: output/spring_1.out
    145:       test:
    146:          suffix: 1
    147:          args: -pep_type {{toar linear}} -pep_conv_norm
    148:       test:
    149:          suffix: 1_stoar
    150:          args: -pep_type stoar -pep_hermitian -pep_conv_rel
    151:       test:
    152:          suffix: 1_qarnoldi
    153:          args: -pep_type qarnoldi -pep_conv_rel

    155:    test:
    156:       suffix: 2
    157:       args: -pep_type jd -pep_nev 4 -n 24 -pep_ncv 18 -pep_target -50 -terse
    158:       requires: complex

    160:    test:
    161:       suffix: 3
    162:       args: -n 300 -pep_hermitian -pep_interval -10.1,-9.5 -pep_type stoar -st_type sinvert -st_pc_type cholesky -terse
    163:       requires: !single

    165:    test:
    166:       suffix: 4
    167:       args: -n 300 -pep_hyperbolic -pep_interval -9.6,-.527 -pep_type stoar -st_type sinvert -st_pc_type cholesky -terse
    168:       requires: !single

    170:    test:
    171:       suffix: 5
    172:       args: -n 300 -pep_hyperbolic -pep_interval -.506,-.3 -pep_type stoar -st_type sinvert -st_pc_type cholesky -pep_stoar_nev 10 -terse
    173:       requires: !single !complex

    175: TEST*/