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: */

 11: static char help[] = "Diagonal eigenproblem.\n\n"
 12:   "The command line options are:\n"
 13:   "  -n <n>, where <n> = matrix dimension.\n"
 14:   "  -seed <s>, where <s> = seed for random number generation.\n\n";

 16: #include <slepceps.h>

 18: int main(int argc,char **argv)
 19: {
 20:   Mat            A;           /* problem matrix */
 21:   EPS            eps;         /* eigenproblem solver context */
 22:   Vec            v0;          /* initial vector */
 23:   PetscRandom    rand;
 24:   PetscReal      tol=PETSC_SMALL;
 25:   PetscInt       n=30,i,Istart,Iend,seed=0x12345678;

 27:   PetscFunctionBeginUser;
 28:   PetscCall(SlepcInitialize(&argc,&argv,NULL,help));

 30:   PetscCall(PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL));
 31:   PetscCall(PetscPrintf(PETSC_COMM_WORLD,"\nDiagonal Eigenproblem, n=%" PetscInt_FMT "\n\n",n));

 33:   PetscCall(MatCreate(PETSC_COMM_WORLD,&A));
 34:   PetscCall(MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,n,n));
 35:   PetscCall(MatSetFromOptions(A));
 36:   PetscCall(MatGetOwnershipRange(A,&Istart,&Iend));
 37:   for (i=Istart;i<Iend;i++) PetscCall(MatSetValue(A,i,i,i+1,INSERT_VALUES));
 38:   PetscCall(MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY));
 39:   PetscCall(MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY));

 41:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 42:                       Solve the eigensystem
 43:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
 44:   PetscCall(EPSCreate(PETSC_COMM_WORLD,&eps));
 45:   PetscCall(EPSSetOperators(eps,A,NULL));
 46:   PetscCall(EPSSetProblemType(eps,EPS_HEP));
 47:   PetscCall(EPSSetTolerances(eps,tol,PETSC_CURRENT));
 48:   PetscCall(EPSSetFromOptions(eps));
 49:   /* set random initial vector */
 50:   PetscCall(MatCreateVecs(A,&v0,NULL));
 51:   PetscCall(PetscRandomCreate(PETSC_COMM_WORLD,&rand));
 52:   PetscCall(PetscRandomSetFromOptions(rand));
 53:   PetscCall(PetscOptionsGetInt(NULL,NULL,"-seed",&seed,NULL));
 54:   PetscCall(PetscRandomSetSeed(rand,seed));
 55:   PetscCall(PetscRandomSeed(rand));
 56:   PetscCall(VecSetRandom(v0,rand));
 57:   PetscCall(EPSSetInitialSpace(eps,1,&v0));
 58:   /* call the solver */
 59:   PetscCall(EPSSolve(eps));

 61:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 62:                     Display solution and clean up
 63:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
 64:   PetscCall(EPSErrorView(eps,EPS_ERROR_RELATIVE,NULL));
 65:   PetscCall(EPSDestroy(&eps));
 66:   PetscCall(MatDestroy(&A));
 67:   PetscCall(VecDestroy(&v0));
 68:   PetscCall(PetscRandomDestroy(&rand));
 69:   PetscCall(SlepcFinalize());
 70:   return 0;
 71: }

 73: /*TEST

 75:    testset:
 76:       args: -eps_nev 4
 77:       requires: !single
 78:       output_file: output/test6_1.out
 79:       test:
 80:          suffix: 1
 81:          args: -eps_type {{krylovschur subspace arnoldi gd}}
 82:       test:
 83:          suffix: 1_power
 84:          args: -eps_type power -eps_max_it 20000
 85:       test:
 86:          suffix: 1_gd2
 87:          args: -eps_type gd -eps_gd_double_expansion
 88:       test:
 89:          suffix: 1_arpack
 90:          args: -eps_type arpack
 91:          requires: arpack
 92:       test:
 93:          suffix: 1_trlan
 94:          args: -eps_type trlan
 95:          requires: trlan

 97: TEST*/