def plot_s_bc(fignum, Bc, S, sym):
    """
    function to plot Squareness,Coercivity

    Parameters
    __________
    fignum : matplotlib figure number
    Bc : list or array coercivity values
    S : list or array of ratio of saturation remanence to saturation
    sym : matplotlib symbol (e.g., 'g^' for green triangles)
    """
    plt.figure(num=fignum)
    plt.plot(Bc, S, sym)
    plt.xlabel('Bc')
    plt.ylabel('Mr/Ms')
    plt.title('Squareness-Coercivity Plot')
    bounds = plt.axis()
    plt.axis([0, bounds[1], 0, 1])