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
a i<qK3!O V(`]hH0;T ans =
NJBSVC b }d. X2? NaN
[<XYU,{R >w. ;A%|N 查看了一下帮助 help hygepdf
0qN`-0Y k O\<zQ2m HYGEPDF Hypergeometric probability density function.
f/Y&)#g>k #zsaQg,
B Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
hV@ N -u^ density function at X with integer parameters M, K, and N.
?M :>2wl Note: The density function is zero unless X is an integer.
4 Fp[94 b ta?NO{* The size of Y is the common size of the input arguments. A scalar input
N:lE{IvRJ functions as a constant matrix of the same size as the other inputs.
Wc@
,#v t'2A)S See also hygecdf, hygeinv, hygernd, hygestat, pdf.
6Q :Wo)^! 'w ,gYW Reference page in Help browser
!=Y E hQ- doc hygepdf
Zu"qTJE/1 l,o'J%<% 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：
7^i7U-A<A {F<0e^* http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m y]Nk^ga:U6 JMB#KzvN[ 直到发现这个例子后才清楚各个参数所代表的具体意义。
y`o j \ bUcp8 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?
T`e`nQ0nn RI*n]HNgy+ p = hygepdf(0:5,100,20,10)
6 /<Hx@r ( &5y p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
T U 6s~ LcGKYl (\K 详细可参见：
;O7 "!\ http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 4`8s] X "mQp#d/' 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
}-fHS;/ /0\g!29l< x = 0:5
T+L=GnYl p = hygepdf(x,100,20,10);
)h@PRDI_ plot(x,p,':k*')
