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
Qqg.z-G %. ,&@GxiU ans =
>z%YK dq 9NwUX h(:( NaN
C[%Qg=< d@ 8M_
O | 查看了一下帮助 help hygepdf
QB X EM= D*2*FDGI HYGEPDF Hypergeometric probability density function.
M>5OC)E XcT!4xG0 Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
t[+bZUS$~ density function at X with integer parameters M, K, and N.
P^"RH&Z QJ Note: The density function is zero unless X is an integer.
_D }3`` T1$p%yQH The size of Y is the common size of the input arguments. A scalar input
swZi
O_85 functions as a constant matrix of the same size as the other inputs.
xz0t8`N oN 2iM}YCV See also hygecdf, hygeinv, hygernd, hygestat, pdf.
kCD] & D+:s{IcL< Reference page in Help browser
AP%R*0] doc hygepdf
QWa@?BO2p v) *MgfS 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：
*K_8=TIA* mW!n%f http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m \& +Y;:6 w( SY 直到发现这个例子后才清楚各个参数所代表的具体意义。
-){6ynqv >3D1:0Sg 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?
hfI=9x/ ?"
4X&6xl p = hygepdf(0:5,100,20,10)
7xO05)bz PcA^ jBgGl p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
@2.
:fK -h7ssf'u[ 详细可参见：
^@8XJ[C,_ http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 *cM=>3ws/ hd'fWFW N 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
@k;65'"Q 7"2BZ x = 0:5
2?%4|@*H? p = hygepdf(x,100,20,10);
%T>@Ldt plot(x,p,':k*')
