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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~Gz9pBv1 s2NBYDi$? 查看了一下帮助 help hygepdf
nD X Em6|e TwI s _r: HYGEPDF Hypergeometric probability density function.
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Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
}zf!mlk density function at X with integer parameters M, K, and N.
~gW^9nWYU Note: The density function is zero unless X is an integer.
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UWqD)6 The size of Y is the common size of the input arguments. A scalar input
Fz,jnV9=j functions as a constant matrix of the same size as the other inputs.
Xpn\TD<_I pvUV5^B(M See also hygecdf, hygeinv, hygernd, hygestat, pdf.
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OO) Reference page in Help browser
M*ZN]9{^. doc hygepdf
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6;r K 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：
AQ@)' +Tu? PuT7k http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m ?YS>_ MN E5)0YYjHZ 直到发现这个例子后才清楚各个参数所代表的具体意义。
IF0!@f 2O[ sRm) 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?
7]zZdqG&p` MkoK(m{7 p = hygepdf(0:5,100,20,10)
O_a^|ln& WIf.;B)L p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
)V2W:M Rh|9F yN 详细可参见：
:t U^ http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 ,P`NtTN- 5X)M)"rq;V 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
Dk^AnMx%_ {<gv1Yht x = 0:5
A8vd@ 0 p = hygepdf(x,100,20,10);
S\8v)|Pr plot(x,p,':k*')
