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
t
;[Me0 A!NT 2YdHZ ans =
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a-7nA Od"-w<' 查看了一下帮助 help hygepdf
s4w<X}O_ pt=[XhxC(> HYGEPDF Hypergeometric probability density function.
NKd):>d% RgEU TpX Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
h~dM*yo; density function at X with integer parameters M, K, and N.
seJc,2Ex Note: The density function is zero unless X is an integer.
NvYgRf}uh l_DP lY The size of Y is the common size of the input arguments. A scalar input
]J~5{srq: functions as a constant matrix of the same size as the other inputs.
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M` pPx See also hygecdf, hygeinv, hygernd, hygestat, pdf.
DK:d'zb l.C {Ar Reference page in Help browser
VGTo$RH doc hygepdf
bBjVot ])e6\) 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：
MEg|AhP X]`\NNx http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m 7m8L!t9 -O2Qz zE& 直到发现这个例子后才清楚各个参数所代表的具体意义。
ofS9h*wrJ |]Ockg[ 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?
aX0sy\Z]j 1V)0+_Yv p = hygepdf(0:5,100,20,10)
qD 2<-E&M/ xU)~)eK p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
$U !w#|& Yh"R# 详细可参见：
x< imMJ http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 w:pc5N>we0 5FzG_ w 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
x'}{^' }/ 8 # 0? x = 0:5
H3MT.Cpd p = hygepdf(x,100,20,10);
|U12 fuQ plot(x,p,':k*')
