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
vkV0On :K,i\ ans =
cxC6n%!;y x_Y!5yg
E NaN
zV3 7$Hb ;%9 |k U 查看了一下帮助 help hygepdf
3AtGy'NTp 1z4OI6$Af HYGEPDF Hypergeometric probability density function.
Yx%Hs5}8 V#$RR!X' Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
h
0Q5-EA density function at X with integer parameters M, K, and N.
'3tCH)s Note: The density function is zero unless X is an integer.
Ykw* &opz 13=AW The size of Y is the common size of the input arguments. A scalar input
*I.f1lz%* functions as a constant matrix of the same size as the other inputs.
%3 -y[f .f2bNnB~pP See also hygecdf, hygeinv, hygernd, hygestat, pdf.
cd_yzpL@}J dt]-,Y
Reference page in Help browser
L|7R9+ZG doc hygepdf
Qx#"q '2 w+|L+ h3L7 超几何分布参数较多，这里关于三个参数的指代不详。又在互联网上查了相关资料，包括该函数的定义式：
#&aqKV Y &)ChQZA http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m n5NsmVW \x E7UU 直到发现这个例子后才清楚各个参数所代表的具体意义。
{rw|# Z>A wKxtre(v Suppose you have a lot of 100 floppy disks and you know that 20 of them are defective. What is the probability of drawing 0 through 5 defective floppy disks if you select 10 at random?
5c0 ZRV# Om\vMd@! p = hygepdf(0:5,100,20,10)
hx %v+/ HyZqUb Ha p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
1~
3_^3OT Vn }0} Jz 详细可参见：
WP MSm<[ http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 IfA Zn_ ,T$U' &; 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
d.d/< q
dBrQC x = 0:5
'9J/T57]e p = hygepdf(x,100,20,10);
ChPmX+.i_ plot(x,p,':k*')
