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
\\qZl)P_ cI*;k.K U ans =
A/s?x>QA xp{tw $ NaN
WT=; : j <'*LRd$1 查看了一下帮助 help hygepdf
7$=In K AkV#J,
3LC HYGEPDF Hypergeometric probability density function.
~0$&3a<n1 D>q9 3;p Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
4HlQ&2O%# density function at X with integer parameters M, K, and N.
n>YKa)|W` Note: The density function is zero unless X is an integer.
`^&OF u ee }Y\%RA The size of Y is the common size of the input arguments. A scalar input
tsjr RMR functions as a constant matrix of the same size as the other inputs.
Yq
K Ceg ;_(4Q*Yx See also hygecdf, hygeinv, hygernd, hygestat, pdf.
_D tV ~>|ziHx Reference page in Help browser
R m( "=( doc hygepdf
&8lZNv8;(p l_p2Riv 超几何分布参数较多，这里关于三个参数的指代不详。又在互联网上查了相关资料，包括该函数的定义式：
i_%_ x* o+' 6`g'8 http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m rILYI;'o g-
gV2$I 直到发现这个例子后才清楚各个参数所代表的具体意义。
4hj|c CrO 4r}51 N\ 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?
WsB ?C&>x 0=YI@@n) p = hygepdf(0:5,100,20,10)
XL ^GZ M= (u ]%\ p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
PW0LG^xp` @VEb { w[H 详细可参见：
upmx $H> http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 h376Be {P z b3t IRH 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
75lA%|
*X Bzf^ivT3L x = 0:5
[/r(__. p = hygepdf(x,100,20,10);
{Sh ;(.u^ plot(x,p,':k*')
