function bar (x, p)
    figure();
    hold on;
    for i = [1:length(p)]
        t = sqrt(2 * p(i) * (p(i) + x(end)));
        y = [-t:2 * t / length(x):t];
        plot(y.^2 / 2 / p(i) - p(i), y);
        t = sqrt(2 * p(i) * (p(i) - x(1)));
        y = [-t:2 * t / length(x):t];
        plot(-(y.^2 / 2 / p(i)) + p(i), y);
    end
end