Actual source code: test12.c

  1: /*
  2:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
  3:    SLEPc - Scalable Library for Eigenvalue Problem Computations
  4:    Copyright (c) 2002-2012, Universitat Politecnica de Valencia, Spain

  6:    This file is part of SLEPc.
  7:       
  8:    SLEPc is free software: you can redistribute it and/or modify it under  the
  9:    terms of version 3 of the GNU Lesser General Public License as published by
 10:    the Free Software Foundation.

 12:    SLEPc  is  distributed in the hope that it will be useful, but WITHOUT  ANY 
 13:    WARRANTY;  without even the implied warranty of MERCHANTABILITY or  FITNESS 
 14:    FOR  A  PARTICULAR PURPOSE. See the GNU Lesser General Public  License  for 
 15:    more details.

 17:    You  should have received a copy of the GNU Lesser General  Public  License
 18:    along with SLEPc. If not, see <http://www.gnu.org/licenses/>.
 19:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 20: */

 22: static char help[] = "Diagonal eigenproblem.\n\n"
 23:   "The command line options are:\n"
 24:   "  -n <n>, where <n> = number of grid subdivisions = matrix dimension.\n"
 25:   "  -seed <s>, where <s> = seed for random number generation.\n\n";

 27: #include <slepceps.h>

 31: PetscErrorCode MyPCApply(PC pc,Vec x,Vec y)
 32: {
 35:   VecCopy(x,y);
 36:   return(0);
 37: }

 41: int main(int argc,char **argv)
 42: {
 43:   Mat            A;           /* problem matrix */
 44:   EPS            eps;         /* eigenproblem solver context */
 45:   Vec            v0;          /* initial vector */
 46:   PetscRandom    rand;
 47:   PetscReal      tol=1000*PETSC_MACHINE_EPSILON;
 48:   PetscInt       n=30,i,Istart,Iend,seed=0x12345678;
 50:   ST             st;
 51:   KSP            ksp;
 52:   PC             pc;

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

 56:   PetscOptionsGetInt(PETSC_NULL,"-n",&n,PETSC_NULL);
 57:   PetscPrintf(PETSC_COMM_WORLD,"\nDiagonal Eigenproblem, n=%d\n\n",n);

 59:   MatCreate(PETSC_COMM_WORLD,&A);
 60:   MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,n,n);
 61:   MatSetFromOptions(A);
 62:   MatSetUp(A);
 63:   MatGetOwnershipRange(A,&Istart,&Iend);
 64:   for (i=Istart;i<Iend;i++) {
 65:     MatSetValue(A,i,i,i+1,INSERT_VALUES);
 66:   }
 67:   MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
 68:   MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);

 70:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
 71:                       Solve the eigensystem
 72:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
 73:   EPSCreate(PETSC_COMM_WORLD,&eps);
 74:   EPSSetOperators(eps,A,PETSC_NULL);
 75:   EPSSetProblemType(eps,EPS_HEP);
 76:   EPSSetTolerances(eps,tol,PETSC_DECIDE);
 77:   EPSSetFromOptions(eps);
 78:   EPSGetST(eps,&st);
 79:   STGetKSP(st,&ksp);
 80:   KSPGetPC(ksp,&pc);
 81:   PCSetType(pc,PCSHELL);
 82:   PCShellSetApply(pc,MyPCApply);
 83:   STPrecondSetMatForPC(st,A);

 85:   /* set random initial vector */
 86:   MatGetVecs(A,&v0,PETSC_NULL);
 87:   PetscRandomCreate(PETSC_COMM_WORLD,&rand);
 88:   PetscRandomSetFromOptions(rand);
 89:   PetscOptionsGetInt(PETSC_NULL,"-seed",&seed,PETSC_NULL);
 90:   PetscRandomSetSeed(rand,seed);
 91:   PetscRandomSeed(rand);
 92:   VecSetRandom(v0,rand);
 93:   EPSSetInitialSpace(eps,1,&v0);
 94:   /* call the solver */
 95:   EPSSolve(eps);

 97:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
 98:                     Display solution and clean up
 99:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
100:   EPSPrintSolution(eps,PETSC_NULL);
101:   EPSDestroy(&eps);
102:   MatDestroy(&A);
103:   VecDestroy(&v0);
104:   PetscRandomDestroy(&rand);
105:   SlepcFinalize();
106:   return 0;
107: }