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
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C9%2}E3Z$) QPT%CW61M NaN
8:)itYE 0X[uXf 查看了一下帮助 help hygepdf
k1 Thjt Ob>M]udn HYGEPDF Hypergeometric probability density function.
Iji9N!Yx 2C_ /T8 Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
7\sR f/ density function at X with integer parameters M, K, and N.
"`8~qZ7k Note: The density function is zero unless X is an integer.
bO\E )%zp e!JC5Al7 The size of Y is the common size of the input arguments. A scalar input
|\_d^U &` functions as a constant matrix of the same size as the other inputs.
bf1EMai" >pq= .)X} See also hygecdf, hygeinv, hygernd, hygestat, pdf.
w.6 Gp;O RYem(%jq Reference page in Help browser
P{_Xg,Z doc hygepdf
; E]^7T hj| P*yKV 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：
La#otuw+? AEr8^6 http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m @Ap~Wok l&LrcM 直到发现这个例子后才清楚各个参数所代表的具体意义。
?R VY%s;g K\a=bA}DG 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?
/agX! E4s oD>j2 6Q p = hygepdf(0:5,100,20,10)
iF1E 5{dH 3ZEV*=+T5 p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
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详细可参见：
xU_Dg56z'& http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 $^;b
1bnO g V-x1s+ 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
v?en-,{A a p[{`u x = 0:5
fF*{\ p = hygepdf(x,100,20,10);
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N>/9 plot(x,p,':k*')
