在用
Matlab绘制各种常用概率分布的密度函数时，都比较简单，唯独超几何分布试了几次都不成功，输出结果总是
GWA!Ab'<U BC$;b>IUA ans =
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查看了一下帮助 help hygepdf
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3A}nNHpN HYGEPDF Hypergeometric probability density function.
44fq1<.K Jv4D^>yj[ Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
C^\*|=*\ density function at X with integer parameters M, K, and N.
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PRuSk-f Note: The density function is zero unless X is an integer.
9,EaN{GM v ACsppa># The size of Y is the common size of the input arguments. A scalar input
P9tQS"Rs functions as a constant matrix of the same size as the other inputs.
u 8k{N N|Cy!E=d See also hygecdf, hygeinv, hygernd, hygestat, pdf.
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Reference page in Help browser
~&j`9jdO j doc hygepdf
(Q +:N; _{Q ?VQvZ 超几何分布参数较多，这里关于三个参数的指代不详。又在互联网上查了相关资料，包括该函数的定义式：
,w b|?>Y Oih 2UrF http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m 1J{z}yPHc a+>W 直到发现这个例子后才清楚各个参数所代表的具体意义。
ap$ tu3j +^&v5[$R Suppose you have a lot of 100 floppy disks and you know that 20 of them are defective. What is the probability of drawing 0 through 5 defective floppy disks if you select 10 at random?
U3j~}H.D1 E][{RTs p = hygepdf(0:5,100,20,10)
vo( j@+dz p,AD!~n` p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
/@nRL 64 \5 v?C 详细可参见：
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*j http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 <% 3SI. l;W y,?p 果然与一般对超几何分布公式字母惯常表示方式有所不同。尝试将上述分布作图如下
6 XOu~+7 %d[xr h x = 0:5
zyp"*0z Ur p = hygepdf(x,100,20,10);
548 [! p4 plot(x,p,':k*')
