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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8#&q$kE 3.)b4T 查看了一下帮助 help hygepdf
nJbbzQ,e l)-Mq@V HYGEPDF Hypergeometric probability density function.
]0r|_)s YQ0)5 } Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
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b density function at X with integer parameters M, K, and N.
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5`nmPO Note: The density function is zero unless X is an integer.
\` w4|T ')N{wSM9Ft The size of Y is the common size of the input arguments. A scalar input
` .2h jO functions as a constant matrix of the same size as the other inputs.
O0PJ6:9P cUO<. See also hygecdf, hygeinv, hygernd, hygestat, pdf.
/(8a~f&%r =KT7n l Reference page in Help browser
UgN28YrW doc hygepdf
s[U r~Wvn /xJqJ_70X 超几何分布参数较多，这里关于三个参数的指代不详。又在互联网上查了相关资料，包括该函数的定义式：
}!i` 0p sFDG) http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m J/A[45OD Ac|5. ?|N 直到发现这个例子后才清楚各个参数所代表的具体意义。
:3$}^uzIq rbZ[ !LA 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?
aV1lJ ;0 p#KW$OQ]8 p = hygepdf(0:5,100,20,10)
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p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
Q# ?wXX47 aJqeD'\> 详细可参见：
C}5M;|%3) http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 ~ np,_yI rNl.7O9b 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
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x = 0:5
y]e> E p = hygepdf(x,100,20,10);
De_ C F8 plot(x,p,':k*')
