static char help[] = "Illustrate how to use mpi FFTW and PETSc-FFTW interface \n\n";

/*
  Compiling the code:
      This code uses the complex numbers version of PETSc, so configure
      must be run to enable this
*/

#include <petscmat.h>
#include <fftw3-mpi.h>

int main(int argc,char **args)
{
  PetscErrorCode ierr;
  PetscMPIInt    rank,size;
  PetscInt       N,DIM;
  Vec            x,y,z;
  Vec            test;

  ierr = PetscInitialize(&argc,&args,(char*)0,help);if (ierr) return ierr;
  ierr = MPI_Comm_size(PETSC_COMM_WORLD, &size);CHKERRQ(ierr);
  ierr = MPI_Comm_rank(PETSC_COMM_WORLD, &rank);CHKERRQ(ierr);
  
  PetscInt i;
  Mat      A;
  PetscInt dim[2];
	
  DIM = 2;
  N = 256;
  dim[0] = N;
  dim[1] = N;
  
  if (!rank) printf("Use PETSc-FFTW interface...%d-DIM: %d\n",(int)DIM,(int)N);
  ierr = MatCreateFFT(PETSC_COMM_WORLD,DIM,dim,MATFFTW,&A);CHKERRQ(ierr);
 
  /* Create vectors that are compatible with parallel layout of A - must call MatCreateVecs()! */
  ierr = MatCreateVecsFFTW(A,&x,&y,&z);CHKERRQ(ierr);
  /* Test vector*/
  //ierr = VecDuplicate(x,&test);CHKERRQ(ierr);
  ierr = MatCreateVecsFFTW(A,&test,NULL,NULL);CHKERRQ(ierr);
	  
  ierr = VecDestroy(&test);CHKERRQ(ierr);
  ierr = VecDestroy(&x);CHKERRQ(ierr);
  ierr = VecDestroy(&y);CHKERRQ(ierr);
  ierr = VecDestroy(&z);CHKERRQ(ierr);
  ierr = MatDestroy(&A);CHKERRQ(ierr);

  ierr = PetscFinalize();
  return 0;
}