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[] = "Eigenproblem for the 1-D Laplacian with constraints. "
      12             :   "Based on ex1.\n"
      13             :   "The command line options are:\n"
      14             :   "  -n <n>, where <n> = number of grid subdivisions = matrix dimension.\n\n";
      15             : 
      16             : #include <slepceps.h>
      17             : 
      18           1 : int main(int argc,char **argv)
      19             : {
      20           1 :   Mat            A;
      21           1 :   EPS            eps;
      22           1 :   EPSType        type;
      23           1 :   Vec            *vi=NULL,*vc=NULL,t;
      24           1 :   PetscInt       n=30,nev=4,i,j,Istart,Iend,nini=0,ncon=0,bs;
      25           1 :   PetscReal      alpha,beta,restart;
      26           1 :   PetscBool      flg,lock;
      27             : 
      28           1 :   PetscFunctionBeginUser;
      29           1 :   PetscCall(SlepcInitialize(&argc,&argv,(char*)0,help));
      30           1 :   PetscCall(PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL));
      31           1 :   PetscCall(PetscOptionsGetInt(NULL,NULL,"-nini",&nini,NULL));
      32           1 :   PetscCall(PetscOptionsGetInt(NULL,NULL,"-ncon",&ncon,NULL));
      33           1 :   PetscCall(PetscPrintf(PETSC_COMM_WORLD,"\n1-D Laplacian Eigenproblem, n=%" PetscInt_FMT " nini=%" PetscInt_FMT " ncon=%" PetscInt_FMT "\n\n",n,nini,ncon));
      34             : 
      35             :   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      36             :      Compute the operator matrix that defines the eigensystem, Ax=kx
      37             :      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
      38             : 
      39           1 :   PetscCall(MatCreate(PETSC_COMM_WORLD,&A));
      40           1 :   PetscCall(MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,n,n));
      41           1 :   PetscCall(MatSetFromOptions(A));
      42             : 
      43           1 :   PetscCall(MatGetOwnershipRange(A,&Istart,&Iend));
      44          31 :   for (i=Istart;i<Iend;i++) {
      45          30 :     if (i>0) PetscCall(MatSetValue(A,i,i-1,-1.0,INSERT_VALUES));
      46          30 :     if (i<n-1) PetscCall(MatSetValue(A,i,i+1,-1.0,INSERT_VALUES));
      47          30 :     PetscCall(MatSetValue(A,i,i,2.0,INSERT_VALUES));
      48             :   }
      49           1 :   PetscCall(MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY));
      50           1 :   PetscCall(MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY));
      51             : 
      52             :   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      53             :                 Create the eigensolver and set various options
      54             :      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
      55           1 :   PetscCall(EPSCreate(PETSC_COMM_WORLD,&eps));
      56           1 :   PetscCall(EPSSetOperators(eps,A,NULL));
      57           1 :   PetscCall(EPSSetProblemType(eps,EPS_HEP));
      58           1 :   PetscCall(EPSSetType(eps,EPSLOBPCG));
      59           1 :   PetscCall(EPSSetWhichEigenpairs(eps,EPS_SMALLEST_REAL));
      60           1 :   PetscCall(EPSSetConvergenceTest(eps,EPS_CONV_ABS));
      61           1 :   PetscCall(EPSSetDimensions(eps,nev,PETSC_DEFAULT,PETSC_DEFAULT));
      62           1 :   PetscCall(EPSLOBPCGSetBlockSize(eps,nev));
      63           1 :   PetscCall(EPSLOBPCGSetRestart(eps,0.7));
      64           1 :   PetscCall(EPSSetTolerances(eps,1e-8,1200));
      65           1 :   PetscCall(EPSSetFromOptions(eps));
      66             : 
      67           1 :   PetscCall(MatCreateVecs(A,&t,NULL));
      68           1 :   if (nini) {
      69           0 :     PetscCall(VecDuplicateVecs(t,nini,&vi));
      70           0 :     for (i=0;i<nini;i++) PetscCall(VecSetRandom(vi[i],NULL));
      71           0 :     PetscCall(EPSSetInitialSpace(eps,nini,vi));
      72             :   }
      73           1 :   if (ncon) {   /* constraints are exact eigenvectors of lowest eigenvalues */
      74           1 :     alpha = PETSC_PI/(n+1);
      75           1 :     beta  = PetscSqrtReal(2.0/(n+1));
      76           1 :     PetscCall(VecDuplicateVecs(t,ncon,&vc));
      77           3 :     for (i=0;i<ncon;i++) {
      78          62 :       for (j=0;j<n;j++) PetscCall(VecSetValue(vc[i],j,PetscSinReal(alpha*(j+1)*(i+1))*beta,INSERT_VALUES));
      79           2 :       PetscCall(VecAssemblyBegin(vc[i]));
      80           2 :       PetscCall(VecAssemblyEnd(vc[i]));
      81             :     }
      82           1 :     PetscCall(EPSSetDeflationSpace(eps,ncon,vc));
      83             :   }
      84             : 
      85             :   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      86             :                       Solve the eigensystem
      87             :      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
      88             : 
      89           1 :   PetscCall(EPSSolve(eps));
      90           1 :   PetscCall(EPSGetType(eps,&type));
      91           1 :   PetscCall(PetscPrintf(PETSC_COMM_WORLD," Solution method: %s\n",type));
      92           1 :   PetscCall(PetscObjectTypeCompare((PetscObject)eps,EPSLOBPCG,&flg));
      93           1 :   if (flg) {
      94           1 :     PetscCall(EPSLOBPCGGetLocking(eps,&lock));
      95           1 :     if (lock) PetscCall(PetscPrintf(PETSC_COMM_WORLD," Using soft locking\n"));
      96           1 :     PetscCall(EPSLOBPCGGetRestart(eps,&restart));
      97           1 :     PetscCall(PetscPrintf(PETSC_COMM_WORLD," LOBPCG Restart parameter=%.4g\n",(double)restart));
      98           1 :     PetscCall(EPSLOBPCGGetBlockSize(eps,&bs));
      99           1 :     PetscCall(PetscPrintf(PETSC_COMM_WORLD," LOBPCG Block size=%" PetscInt_FMT "\n",bs));
     100             :   }
     101             : 
     102             :   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     103             :                     Display solution and clean up
     104             :      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
     105             : 
     106           1 :   PetscCall(EPSErrorView(eps,EPS_ERROR_RELATIVE,NULL));
     107           1 :   PetscCall(EPSDestroy(&eps));
     108           1 :   PetscCall(MatDestroy(&A));
     109           1 :   PetscCall(VecDestroyVecs(nini,&vi));
     110           1 :   PetscCall(VecDestroyVecs(ncon,&vc));
     111           1 :   PetscCall(VecDestroy(&t));
     112           1 :   PetscCall(SlepcFinalize());
     113             :   return 0;
     114             : }
     115             : 
     116             : /*TEST
     117             : 
     118             :    testset:
     119             :       args: -ncon 2
     120             :       output_file: output/test24_1.out
     121             :       test:
     122             :          suffix: 1
     123             :          requires: !single
     124             :       test:
     125             :          suffix: 2_cuda
     126             :          args: -mat_type aijcusparse
     127             :          requires: cuda !single
     128             : 
     129             : TEST*/