def get_delta_pal(b, b_star):
    """
    input: b, b_star (actual and corrected slope)
    output: delta_pal
    """
    delta_pal = numpy.abs(old_div((b - b_star), b)) * 100
    return delta_pal
input: b, b_star (actual and corrected slope)
    output: delta_pal