psi_eqfile_cart Function

  real function psi_eqfile_cart (self, r, theta) result(psi)
    implicit none
    class(abstract_eqfile_cart_geo_type), intent(in) :: self
    real, intent (in) :: r, theta
    if (is_zero(r)) then
       psi = self%psi_0
    else if (exactly_equal(r, 1.) .and. is_zero(theta)) then
       psi = self%psi_a
    else
       psi = self%eqitem(r, theta, self%eqpsi_2d, '?')
    end if
  end function psi_eqfile_cart