do_write_eigenfunc Subroutine

  subroutine do_write_eigenfunc(file_id, write_text, phi0)
    use mp, only: proc0
    use file_utils, only: open_output_file, close_output_file
    use fields_arrays, only: phi, apar, bpar
    use kt_grids, only: ntheta0, naky, theta0, aky
    use theta_grid, only: theta, ntgrid
    use gs2_io, only: nc_eigenfunc
    use dist_fn, only: def_parity, even
    use run_parameters, only: has_apar
    implicit none
    !> NetCDF ID of the file to write to
    integer, intent(in) :: file_id
    !> If true, write text file
    logical, intent(in) :: write_text
    !> The normalising factor for the fields that is actually used. See
    !> [[gs2_diagnostics_knobs:write_eigenfunc]] for more details
    complex, dimension (:,:), intent(inout) :: phi0
    integer :: it, ik, ig, unit

    if(.not.proc0) return

    !Should this actually use igomega instead of 0?
    !What if fphi==0? --> See where statements below
    phi0 = phi(0,:,:)

    !This looks like a hack for the case where we know we've forced phi(theta=0) to be 0
    !this could probably be better addressed by the use of igomega above
    if (def_parity .and. has_apar .and. (.not. even)) phi0 = apar(0, :, :)

    !Address locations where phi0=0 by using next point
    where (abs(phi0) < 10.0*epsilon(0.0)) 
       phi0 = phi(1,:,:)/(theta(1)-theta(0))
    end where

    !Check again if any locations are 0, this could be true if fphi (or fapar)
    !is zero.
    where (abs(phi0) < 10.0*epsilon(0.0)) 
       phi0 = 1.0
    end where

    if (write_text) then
       call open_output_file (unit, ".eigenfunc")
       do ik = 1, naky
          do it = 1, ntheta0
             do ig = -ntgrid, ntgrid
                write (unit, "(9(1x,e12.5))") &
                     theta(ig), theta0(it,ik), aky(ik), &
                     phi(ig,it,ik)/phi0(it,ik), &
                     apar(ig,it,ik)/phi0(it,ik), &
                     bpar(ig,it,ik)/phi0(it,ik)
             end do
             write (unit, "()")
          end do
       end do
       call close_output_file (unit)
    end if

    call nc_eigenfunc (file_id, phi0)
  end subroutine do_write_eigenfunc