MATLAB概率密度

pulbieup

[f,xi]=ksdensity(x);

plot(xi,f) ;

概率密度是plot(xi,f)曲线的高度，它乘以底边（xi）的间距（得到面积）才是概率，当xi区间越小时，fi必然会越大，甚至于单个fi超过1。曲线下面的总面积必然为1。

a;          %样本
) D) u9 R4 c8 r8 M+ Wx=linspace(min(a),max(a),30);      %分组
yy=hist(a,x);   %频数
+ y4 N2 W2 z" ]+ e: E& Ebar(x,yy/length(a));

用hist得到的是次数，它除以总的次数得到的是频率，而后者与概率的含义相同。

histfit(data);

will plot the data as a histogram and show a smooth curve of the best fit gaussian to it.

% 下面的还没搞清楚？？

[mu, sigma] = normfit(data);

pd = fitdist(data,'normal');

will give the mean (mu) and standard deviation (sigma) of that same set of data, which are used by histfit to generate the fitted curve.

+ T* I) k- O9 _) _' U

CCxiaom

MATLAB概率密度