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
{\(G^B*\ SxY z)aF~ ans =
%NQ%6 B 6X@z(EEL NaN
hH`x*:Qja Be|! S_Y P 查看了一下帮助 help hygepdf
zgGysjV fv7VDo8vb HYGEPDF Hypergeometric probability density function.
4fKvB@O@. 9} 6 _B| Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
j OV6 % density function at X with integer parameters M, K, and N.
@ SD XJJ h Note: The density function is zero unless X is an integer.
P7-k!p" Ve(<s
The size of Y is the common size of the input arguments. A scalar input
|1%% c
% functions as a constant matrix of the same size as the other inputs.
:Tpf8 iLnW5yy See also hygecdf, hygeinv, hygernd, hygestat, pdf.
%AO6 = r4mh:T4i Reference page in Help browser
zdwQpB,+^ doc hygepdf
? r !kKMZ "zq'nV= 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：
lf`ULY4{ B[ZQn]y http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m &MpLm& |X=p`iz1& 直到发现这个例子后才清楚各个参数所代表的具体意义。
{>hxmn
9^!.!%6O$ 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?
9CS" s_ 0Y e/ p = hygepdf(0:5,100,20,10)
QT+kCN qA '^b~ p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
(n k g ~S('\h)1 详细可参见：
0cG[<\qT http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 2-'_Nwkl* W%+0 2_/) 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
m^oG9&" ; 'yCVB&`b x = 0:5
.h
<=C&Yg p = hygepdf(x,100,20,10);
vT#R>0@m i plot(x,p,':k*')
