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
rCi7q]_ B~QX{ ans =
b|U&{I>TH )$Xd#bzD| NaN
jnsV'@v8Nj ."Wdp f`~ 查看了一下帮助 help hygepdf
]\w0u7} =k6zUw;5 U HYGEPDF Hypergeometric probability density function.
e^Q$Tog< Hq[d!qc Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
'uS!rKkQlu density function at X with integer parameters M, K, and N.
*`OgwMr)M Note: The density function is zero unless X is an integer.
|ybW BlUl5mP}> The size of Y is the common size of the input arguments. A scalar input
cZI )lX functions as a constant matrix of the same size as the other inputs.
5!u.w Wc [@, See also hygecdf, hygeinv, hygernd, hygestat, pdf.
^N}zePy0 V{@
xhW0 Reference page in Help browser
XlIRedZ{ doc hygepdf
g\;AU2?p7 yz r>]"o 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：
`RDl k N p9N# m? http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m >ch{u{i6 7 ^,C=2
直到发现这个例子后才清楚各个参数所代表的具体意义。
ktLXL;~X +^tq?PfE 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?
yL/EIN }YJ(|z"" p = hygepdf(0:5,100,20,10)
!]1X0wo\ g*C&Pr3 p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
k%-_z}:3V ^]c/hb|X 详细可参见：
W$LaXytmak http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 Su`LB z" @k:f(c 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
IPmSkK #~ ?Q?" x = 0:5
}@MOkj p = hygepdf(x,100,20,10);
9 2_F 8y*D plot(x,p,':k*')
