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
LUNs |\& 1N!g`=} ans =
qffSq](D. %vt SeJ NaN
4nH91Z9= k |3(dXLG 查看了一下帮助 help hygepdf
1=Zw=ufqV \( <{)GpBi HYGEPDF Hypergeometric probability density function.
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3 RQCQG a^cP Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
hIQ[:f density function at X with integer parameters M, K, and N.
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Oky Note: The density function is zero unless X is an integer.
6KCmswvE b8Rh|"J)d The size of Y is the common size of the input arguments. A scalar input
7NB 9Vu|gD functions as a constant matrix of the same size as the other inputs.
&}0wzcMg 0@K:Tq-mF See also hygecdf, hygeinv, hygernd, hygestat, pdf.
A dEbyL RzRvu]]8 Reference page in Help browser
(oitCIV doc hygepdf
d^5SeCs6 Z 'NbHwW} 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：
r!$NZ2I ; eF4J http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m P%`R7yk ]cqZ!4? _ 直到发现这个例子后才清楚各个参数所代表的具体意义。
9G&l qfX: S"^KJUUc Suppose you have a lot of 100 floppy disks and you know that 20 of them are defective. What is the probability of drawing 0 through 5 defective floppy disks if you select 10 at random?
]KK ZbEO |SP.S 0.y p = hygepdf(0:5,100,20,10)
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mK zrU$S WU p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
Bdq"6SK> ]Ec[")"kT 详细可参见：
StZRc\k http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 j]B $(pt >?9 WeXG 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
e#6&uFce o`K^Wy~+k# x = 0:5
UW/3{2 p = hygepdf(x,100,20,10);
R;E"Qdt plot(x,p,':k*')
