Date: 2017-05-17T08:26:16+00:00

Actual source code: test12.c
slepc-3.7.4 2017-05-17
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      1: /*
      2:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      3:    SLEPc - Scalable Library for Eigenvalue Problem Computations
      4:    Copyright (c) 2002-2016, Universitat Politecnica de Valencia, Spain

      6:    This file is part of SLEPc.

      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. Illustrates use of shell preconditioner.\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 PCApply_User(PC pc,Vec x,Vec y)
     32: {

     36:   VecCopy(x,y);
     37:   return(0);
     38: }

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

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

     57:   PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL);
     58:   PetscPrintf(PETSC_COMM_WORLD,"\nDiagonal Eigenproblem, n=%D\n\n",n);

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

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

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

     98:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     99:                     Display solution and clean up
    100:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
    101:   EPSErrorView(eps,EPS_ERROR_RELATIVE,NULL);
    102:   EPSDestroy(&eps);
    103:   MatDestroy(&A);
    104:   VecDestroy(&v0);
    105:   PetscRandomDestroy(&rand);
    106:   SlepcFinalize();
    107:   return ierr;
    108: }