function Lagr
    clf
    hold on
    grid on
    axis ([-1, 1, -1, 1]/2);
    t = -0.5:0.1:0.5;
    hold on
    plot (t,t,t,t-4/27)
    x0 = 1/4;
    y0 = 1/8;
    plot(x0, y0, 'ko', 'MarkerFaceColor', [0,0,0])
    y = dsolve ('-8*(Dy)^3 + 12*(Dy)^2 + 27*(y-x)', 'y(1/4) = 1/8', 'x');
    c = double(solve('(1/8-c)^2 = (1/4-c)^3', 'c'));
    x1 = c(1):0.1:x0+1;
    x2 = c(2):0.1:x0+1;
    x3 = c(3):0.1:x0+1;
    y1 = subs(y(1), 'x', x1);
    y2 = subs(y(2), 'x', x2);
    y3 = subs(y(3), 'x', x3);
    plot (x1, y1, x2, y2, x3, y3)
end

