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
e`Yx]3;u( rNZN}g ans =
lqu1H& [
h%ci3 NaN
8on2 BC2 ji">} - 查看了一下帮助 help hygepdf
[_${N,1 OrHnz981K HYGEPDF Hypergeometric probability density function.
Nk]r2^. z[ eRD s?n3F Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
zX(p\ NU density function at X with integer parameters M, K, and N.
2c} >} A 4 Note: The density function is zero unless X is an integer.
E_-CsL% pi+m`O The size of Y is the common size of the input arguments. A scalar input
w$ {=]h*2 functions as a constant matrix of the same size as the other inputs.
J8( v 65 c^I_~OwaE See also hygecdf, hygeinv, hygernd, hygestat, pdf.
Uw4KdC GYC c)Guc Reference page in Help browser
Z5\ u9E"] doc hygepdf
'% kk&&3' /)6<`S( 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：
@TsOc 0?- y~;Kf0~ http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m %KRAcCa7 Pr/K5aJeg 直到发现这个例子后才清楚各个参数所代表的具体意义。
><5tnBP|+L u|APx8?"o 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?
`2 Vc*R a+IU<O-J? p = hygepdf(0:5,100,20,10)
:jgwp~l 8D)2/$NsY} p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
Id|38 9 *Q/3| 详细可参见：
I C37f[Q http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 h9RG?r1 79=w]y 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
V # =o< (+(YO\ng6 x = 0:5
Q]A;VNx p = hygepdf(x,100,20,10);
u:NSPAD) plot(x,p,':k*')
