添加注释.

Signed-off-by: lion.chan <cy187lion@sina.com>

Algorithm/Statistics/高斯分布.md

@@ -21,9 +21,12 @@ $$G(x,y)=Ae^{(-\frac{(x-x_0)^2}{2\sigma_x^2}+\frac{(y-y_0)^2}{2\sigma_y^2})}$$
 Matlab 图像绘制程序：
 
 ```m
+% A=1
+% σx=σy=1
+% x0=y0=0
 x1 = [0:0.1:10];
 y1 = [0:0.1:10];
 [x,y] = meshgrid(x1,y1);
-gxy = exp(-((x-5).*(x-5)+(y-5).*(y-5))/18);
+gxy = exp(-((x-5).*(x-5)+(y-5).*(y-5))/2);
 surf(x, y, gxy);
 ```