Line data    Source code

       1             : /*
       2             :    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
       3             :    SLEPc - Scalable Library for Eigenvalue Problem Computations
       4             :    Copyright (c) 2002-, Universitat Politecnica de Valencia, Spain
       5             : 
       6             :    This file is part of SLEPc.
       7             :    SLEPc is distributed under a 2-clause BSD license (see LICENSE).
       8             :    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
       9             : */
      10             : 
      11             : static char help[] = "Illustrates region filtering in PEP (based on spring).\n"
      12             :   "The command line options are:\n"
      13             :   "  -n <n> ... number of grid subdivisions.\n"
      14             :   "  -mu <value> ... mass (default 1).\n"
      15             :   "  -tau <value> ... damping constant of the dampers (default 10).\n"
      16             :   "  -kappa <value> ... damping constant of the springs (default 5).\n\n";
      17             : 
      18             : #include <slepcpep.h>
      19             : 
      20           3 : int main(int argc,char **argv)
      21             : {
      22           3 :   Mat            M,C,K,A[3];      /* problem matrices */
      23           3 :   PEP            pep;             /* polynomial eigenproblem solver context */
      24           3 :   RG             rg;
      25           3 :   PetscInt       n=30,Istart,Iend,i;
      26           3 :   PetscReal      mu=1.0,tau=10.0,kappa=5.0;
      27             : 
      28           3 :   PetscFunctionBeginUser;
      29           3 :   PetscCall(SlepcInitialize(&argc,&argv,NULL,help));
      30             : 
      31           3 :   PetscCall(PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL));
      32           3 :   PetscCall(PetscOptionsGetReal(NULL,NULL,"-mu",&mu,NULL));
      33           3 :   PetscCall(PetscOptionsGetReal(NULL,NULL,"-tau",&tau,NULL));
      34           3 :   PetscCall(PetscOptionsGetReal(NULL,NULL,"-kappa",&kappa,NULL));
      35           3 :   PetscCall(PetscPrintf(PETSC_COMM_WORLD,"\nDamped mass-spring system, n=%" PetscInt_FMT " mu=%g tau=%g kappa=%g\n\n",n,(double)mu,(double)tau,(double)kappa));
      36             : 
      37             :   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      38             :      Compute the matrices that define the eigensystem, (k^2*M+k*C+K)x=0
      39             :      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
      40             : 
      41             :   /* K is a tridiagonal */
      42           3 :   PetscCall(MatCreate(PETSC_COMM_WORLD,&K));
      43           3 :   PetscCall(MatSetSizes(K,PETSC_DECIDE,PETSC_DECIDE,n,n));
      44           3 :   PetscCall(MatSetFromOptions(K));
      45             : 
      46           3 :   PetscCall(MatGetOwnershipRange(K,&Istart,&Iend));
      47          93 :   for (i=Istart;i<Iend;i++) {
      48          90 :     if (i>0) PetscCall(MatSetValue(K,i,i-1,-kappa,INSERT_VALUES));
      49          90 :     PetscCall(MatSetValue(K,i,i,kappa*3.0,INSERT_VALUES));
      50          90 :     if (i<n-1) PetscCall(MatSetValue(K,i,i+1,-kappa,INSERT_VALUES));
      51             :   }
      52             : 
      53           3 :   PetscCall(MatAssemblyBegin(K,MAT_FINAL_ASSEMBLY));
      54           3 :   PetscCall(MatAssemblyEnd(K,MAT_FINAL_ASSEMBLY));
      55             : 
      56             :   /* C is a tridiagonal */
      57           3 :   PetscCall(MatCreate(PETSC_COMM_WORLD,&C));
      58           3 :   PetscCall(MatSetSizes(C,PETSC_DECIDE,PETSC_DECIDE,n,n));
      59           3 :   PetscCall(MatSetFromOptions(C));
      60             : 
      61           3 :   PetscCall(MatGetOwnershipRange(C,&Istart,&Iend));
      62          93 :   for (i=Istart;i<Iend;i++) {
      63          90 :     if (i>0) PetscCall(MatSetValue(C,i,i-1,-tau,INSERT_VALUES));
      64          90 :     PetscCall(MatSetValue(C,i,i,tau*3.0,INSERT_VALUES));
      65          90 :     if (i<n-1) PetscCall(MatSetValue(C,i,i+1,-tau,INSERT_VALUES));
      66             :   }
      67             : 
      68           3 :   PetscCall(MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY));
      69           3 :   PetscCall(MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY));
      70             : 
      71             :   /* M is a diagonal matrix */
      72           3 :   PetscCall(MatCreate(PETSC_COMM_WORLD,&M));
      73           3 :   PetscCall(MatSetSizes(M,PETSC_DECIDE,PETSC_DECIDE,n,n));
      74           3 :   PetscCall(MatSetFromOptions(M));
      75           3 :   PetscCall(MatGetOwnershipRange(M,&Istart,&Iend));
      76          93 :   for (i=Istart;i<Iend;i++) PetscCall(MatSetValue(M,i,i,mu,INSERT_VALUES));
      77           3 :   PetscCall(MatAssemblyBegin(M,MAT_FINAL_ASSEMBLY));
      78           3 :   PetscCall(MatAssemblyEnd(M,MAT_FINAL_ASSEMBLY));
      79             : 
      80             :   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      81             :                     Create a region for filtering
      82             :      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
      83             : 
      84           3 :   PetscCall(RGCreate(PETSC_COMM_WORLD,&rg));
      85           3 :   PetscCall(RGSetType(rg,RGINTERVAL));
      86             : #if defined(PETSC_USE_COMPLEX)
      87           3 :   PetscCall(RGIntervalSetEndpoints(rg,-47.0,-35.0,-0.001,0.001));
      88             : #else
      89             :   PetscCall(RGIntervalSetEndpoints(rg,-47.0,-35.0,-0.0,0.0));
      90             : #endif
      91             : 
      92             :   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      93             :                 Create the eigensolver and solve the problem
      94             :      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
      95             : 
      96           3 :   PetscCall(PEPCreate(PETSC_COMM_WORLD,&pep));
      97           3 :   PetscCall(PEPSetRG(pep,rg));
      98           3 :   A[0] = K; A[1] = C; A[2] = M;
      99           3 :   PetscCall(PEPSetOperators(pep,3,A));
     100           3 :   PetscCall(PEPSetTolerances(pep,PETSC_SMALL,PETSC_CURRENT));
     101           3 :   PetscCall(PEPSetFromOptions(pep));
     102           3 :   PetscCall(PEPSolve(pep));
     103             : 
     104             :   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     105             :                     Display solution and clean up
     106             :      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
     107             : 
     108           3 :   PetscCall(PEPErrorView(pep,PEP_ERROR_BACKWARD,NULL));
     109           3 :   PetscCall(PEPDestroy(&pep));
     110           3 :   PetscCall(MatDestroy(&M));
     111           3 :   PetscCall(MatDestroy(&C));
     112           3 :   PetscCall(MatDestroy(&K));
     113           3 :   PetscCall(RGDestroy(&rg));
     114           3 :   PetscCall(SlepcFinalize());
     115             :   return 0;
     116             : }
     117             : 
     118             : /*TEST
     119             : 
     120             :    test:
     121             :       args: -pep_nev 8 -pep_type {{toar linear qarnoldi}}
     122             :       suffix: 1
     123             :       requires: !single
     124             :       output_file: output/test12_1.out
     125             : 
     126             : TEST*/