fig = plt.figure(figsize=(8, 8))
ax = fig.gca(projection='3d')
t = np.linspace(-3, 2, 31)
s = np.linspace(-3, 2, 31)
T, S = np.meshgrid(t, s)
ax.plot_surface(T * T, sqrt2 * T * S, S * S, cmap=cm.jet, rstride=1, cstride=1)
ax.set_xlabel('$t^2$')
ax.set_ylabel('$\\sqrt{2} s t$')
ax.set_zlabel('$s^2$')
ax.set_title('line $s = t$ in $\\cal F$')
plt.show()
colored wireframe plot in matplotlib