Actual source code: test12.c

slepc-3.17.0 2022-03-31
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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:   PetscFunctionReturn(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;

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

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

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

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

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

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