Date: 2023-01-26T12:18:48+00:00

Actual source code: test12.c
slepc-3.18.2 2023-01-26
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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: {
     21:   VecCopy(x,y);
     22:   return 0;
     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;

     38:   SlepcInitialize(&argc,&argv,(char*)0,help);

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

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

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

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

     78:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     79:                     Display solution and clean up
     80:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
     81:   EPSErrorView(eps,EPS_ERROR_RELATIVE,NULL);
     82:   EPSDestroy(&eps);
     83:   MatDestroy(&A);
     84:   VecDestroy(&v0);
     85:   PetscRandomDestroy(&rand);
     86:   SlepcFinalize();
     87:   return 0;
     88: }

     90: /*TEST

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

    105: TEST*/