program test

  complex, dimension(:), allocatable :: a, b, c
  real, dimension(:), allocatable :: x

  complex, parameter :: zi = (0., 1.)
  real, parameter :: pi = 3.1415926535897931
  complex :: res

  integer :: k1, k2, nx, j

  namelist /input/k1, k2, nx

  open (unit=11, file='test.in', status='old')
  read (11, input)
  close (11)

  allocate (a(-nx/2:nx/2)) ; a = 0.
  allocate (b(-nx/2:nx/2)) ; b = 0.
  allocate (c(-nx/2:nx/2)) ; c = 0.
  allocate (x(-nx/2:nx/2)) ; x = 0.
  
  do j = -nx/2, nx/2
     x(j) = 2*pi*j/nx
  end do

  a = (exp(zi*k1*x)+exp(-zi*k1*x))
  b = (exp(zi*k2*x)+exp(-zi*k2*x))

!
! This is the inner product
!
  res = sum(a(-nx/2+1:) * conjg(b(-nx/2+1:)))/(2*nx)

  res = 0.
  do j=-nx/2+1, nx/2
     res = res + a(j)*conjg(b(j))
  end do
  res = res/(2*nx)
  
  write(*,*) res

  open (unit=12, file='test.out')
  do j = -nx/2, nx/2
     write(12,*) 2*j*pi/nx, real(a(j)), real(b(j)), &
          aimag(a(j)), aimag(b(j))
  end do
  close (12)

end program test