Update index.html

threejs/attractors/lorenz-variation/index.html

@@ -43,7 +43,7 @@
             \left\{ \begin{eqnarray*}
             x'&=&\sigma (-x + y) + \sin\left(\frac{y}{5}\right) \sin\left(\frac{z}{5}\right)  \\
             y'&=& -x z + \rho x - y  + \sin\left(\frac{x}{5}\right) \sin\left(\frac{z}{5}\right)   \\
-            y'&=& x y - \beta z + \cos\left(\frac{y}{5}\right) \cos\left(\frac{x}{5}\right)
+            z'&=& x y - \beta z + \cos\left(\frac{y}{5}\right) \cos\left(\frac{x}{5}\right)
             \end{eqnarray*}\right.
             \]
         </p>