Date: 2024-12-02T08:57:03+00:00

Actual source code: test12.c
slepc-3.22.2 2024-12-02
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      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. Illustrates use of shell preconditioner.\n\n"
     12:   "The command line options are:\n"
     13:   "  -n <n>, where <n> = number of grid subdivisions = matrix dimension.\n"
     14:   "  -seed <s>, where <s> = seed for random number generation.\n\n";

     16: #include <slepceps.h>

     18: PetscErrorCode PCApply_User(PC pc,Vec x,Vec y)
     19: {
     20:   PetscFunctionBeginUser;
     21:   PetscCall(VecCopy(x,y));
     22:   PetscFunctionReturn(PETSC_SUCCESS);
     23: }

     25: int main(int argc,char **argv)
     26: {
     27:   Mat            A;           /* problem matrix */
     28:   EPS            eps;         /* eigenproblem solver context */
     29:   Vec            v0;          /* initial vector */
     30:   PetscRandom    rand;
     31:   PetscReal      tol=PETSC_SMALL;
     32:   PetscInt       n=30,i,Istart,Iend,seed=0x12345678;
     33:   ST             st;
     34:   KSP            ksp;
     35:   PC             pc;

     37:   PetscFunctionBeginUser;
     38:   PetscCall(SlepcInitialize(&argc,&argv,NULL,help));

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

     43:   PetscCall(MatCreate(PETSC_COMM_WORLD,&A));
     44:   PetscCall(MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,n,n));
     45:   PetscCall(MatSetFromOptions(A));
     46:   PetscCall(MatGetOwnershipRange(A,&Istart,&Iend));
     47:   for (i=Istart;i<Iend;i++) PetscCall(MatSetValue(A,i,i,i+1,INSERT_VALUES));
     48:   PetscCall(MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY));
     49:   PetscCall(MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY));

     51:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     52:                       Solve the eigensystem
     53:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
     54:   PetscCall(EPSCreate(PETSC_COMM_WORLD,&eps));
     55:   PetscCall(EPSSetOperators(eps,A,NULL));
     56:   PetscCall(EPSSetProblemType(eps,EPS_HEP));
     57:   PetscCall(EPSSetTolerances(eps,tol,PETSC_CURRENT));
     58:   PetscCall(EPSSetFromOptions(eps));
     59:   PetscCall(EPSGetST(eps,&st));
     60:   PetscCall(STGetKSP(st,&ksp));
     61:   PetscCall(KSPGetPC(ksp,&pc));
     62:   PetscCall(PCSetType(pc,PCSHELL));
     63:   PetscCall(PCShellSetApply(pc,PCApply_User));

     65:   /* set random initial vector */
     66:   PetscCall(MatCreateVecs(A,&v0,NULL));
     67:   PetscCall(PetscRandomCreate(PETSC_COMM_WORLD,&rand));
     68:   PetscCall(PetscRandomSetFromOptions(rand));
     69:   PetscCall(PetscOptionsGetInt(NULL,NULL,"-seed",&seed,NULL));
     70:   PetscCall(PetscRandomSetSeed(rand,seed));
     71:   PetscCall(PetscRandomSeed(rand));
     72:   PetscCall(VecSetRandom(v0,rand));
     73:   PetscCall(EPSSetInitialSpace(eps,1,&v0));
     74:   /* call the solver */
     75:   PetscCall(EPSSolve(eps));

     77:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     78:                     Display solution and clean up
     79:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
     80:   PetscCall(EPSErrorView(eps,EPS_ERROR_RELATIVE,NULL));
     81:   PetscCall(EPSDestroy(&eps));
     82:   PetscCall(MatDestroy(&A));
     83:   PetscCall(VecDestroy(&v0));
     84:   PetscCall(PetscRandomDestroy(&rand));
     85:   PetscCall(SlepcFinalize());
     86:   return 0;
     87: }

     89: /*TEST

     91:    testset:
     92:       requires: !single
     93:       output_file: output/test12_1.out
     94:       test:
     95:          suffix: 1
     96:          args: -eps_type {{krylovschur subspace arnoldi gd jd}} -eps_nev 4
     97:       test:
     98:          suffix: 1_power
     99:          args: -eps_type power -eps_max_it 10000 -eps_nev 4
    100:       test:
    101:          suffix: 1_gd2
    102:          args: -eps_type gd -eps_gd_double_expansion -eps_nev 4

    104: TEST*/