Lorenz

Sigma = 10;r=28;
solution = NDSolve[{
x'[t] == Sigma (y[t] - x[t]),
y'[t] == r x[t] - y[t] - x[t] z[t],
z'[t] == x[t] y[t] - 8/3 z[t], x[0] == z[0] == 0, y[0] == 2},
{x, y, z}, {t, 0, 35}];
ParametricPlot3D[Evaluate[{x[t], y[t], z[t]} /. solution], {t, 0, 35}]