eqitem_cart Function

  real function eqitem_cart(self, r_in, theta_in, f, char) result(fstar)
    use mp, only: mp_abort
    implicit none
    class(abstract_eqfile_cart_geo_type), intent(in) :: self
    real, intent (in) :: r_in, theta_in
    real, dimension(:, :), intent(in) :: f
    character(1), intent(in) :: char
    integer :: istar, jstar
    real :: r, thet, r_pos, z_pos
    UNUSED_DUMMY(char)
    associate(dim_1 => self%eq_R, dim_2 => self%eq_Z)
      !Copy input r to avoid any modification
      r = r_in ; thet = mod2pi(theta_in)
      r_pos = self%Rpos(r, thet) ; z_pos = self%Zpos(r, thet)

      ! ensure point is on R mesh
      if (r_pos >= dim_1(self%nw) .or. r_pos <= dim_1(1)) then
         write(*,*) r, theta_in, dim_1(self%nw), r_pos
         call mp_abort('No evaluation of eqitem allowed outside or on edge of R domain', .true.)
      end if

      ! ensure point is on Z mesh
      if (z_pos >= dim_2(self%nh) .or. z_pos <= dim_2(1)) then
         write(*,*) r, theta_in, dim_2(1), dim_2(self%nh), z_pos
         call mp_abort('No evaluation of eqitem allowed outside or on edge of Z domain', .true.)
      end if

      istar = find_lower_bound(r_pos, dim_1, 0)
      jstar = find_lower_bound(z_pos, dim_2, 0)
      fstar = bilinear_interpolate(f, dim_1, dim_2, istar, jstar, r_pos, z_pos)
    end associate
  end function eqitem_cart