Actual source code: test6.c

slepc-3.9.0 2018-04-12
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  1: /*
  2:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
  3:    SLEPc - Scalable Library for Eigenvalue Problem Computations
  4:    Copyright (c) 2002-2018, 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.\n\n"
 12:   "The command line options are:\n"
 13:   "  -n <n>, where <n> = matrix dimension.\n"
 14:   "  -seed <s>, where <s> = seed for random number generation.\n\n";

 16: #include <slepceps.h>

 18: int main(int argc,char **argv)
 19: {
 20:   Mat            A;           /* problem matrix */
 21:   EPS            eps;         /* eigenproblem solver context */
 22:   Vec            v0;          /* initial vector */
 23:   PetscRandom    rand;
 24:   PetscReal      tol=1000*PETSC_MACHINE_EPSILON;
 25:   PetscInt       n=30,i,Istart,Iend,seed=0x12345678;

 28:   SlepcInitialize(&argc,&argv,(char*)0,help);if (ierr) return ierr;

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

 33:   MatCreate(PETSC_COMM_WORLD,&A);
 34:   MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,n,n);
 35:   MatSetFromOptions(A);
 36:   MatSetUp(A);
 37:   MatGetOwnershipRange(A,&Istart,&Iend);
 38:   for (i=Istart;i<Iend;i++) {
 39:     MatSetValue(A,i,i,i+1,INSERT_VALUES);
 40:   }
 41:   MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
 42:   MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);

 44:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 45:                       Solve the eigensystem
 46:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
 47:   EPSCreate(PETSC_COMM_WORLD,&eps);
 48:   EPSSetOperators(eps,A,NULL);
 49:   EPSSetProblemType(eps,EPS_HEP);
 50:   EPSSetTolerances(eps,tol,PETSC_DEFAULT);
 51:   EPSSetFromOptions(eps);
 52:   /* set random initial vector */
 53:   MatCreateVecs(A,&v0,NULL);
 54:   PetscRandomCreate(PETSC_COMM_WORLD,&rand);
 55:   PetscRandomSetFromOptions(rand);
 56:   PetscOptionsGetInt(NULL,NULL,"-seed",&seed,NULL);
 57:   PetscRandomSetSeed(rand,seed);
 58:   PetscRandomSeed(rand);
 59:   VecSetRandom(v0,rand);
 60:   EPSSetInitialSpace(eps,1,&v0);
 61:   /* call the solver */
 62:   EPSSolve(eps);

 64:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 65:                     Display solution and clean up
 66:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
 67:   EPSErrorView(eps,EPS_ERROR_RELATIVE,NULL);
 68:   EPSDestroy(&eps);
 69:   MatDestroy(&A);
 70:   VecDestroy(&v0);
 71:   PetscRandomDestroy(&rand);
 72:   SlepcFinalize();
 73:   return ierr;
 74: }