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
8Z |A'M ?e{hid g ans =
Ab
#}BHI >:Y"DX- NaN
~nJ"#Q_T 'XJqh|G 查看了一下帮助 help hygepdf
?K\ r-J!Y ;
,Nvg6c HYGEPDF Hypergeometric probability density function.
d\ I6Wn bL`># M_^ Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
^jb jH I& density function at X with integer parameters M, K, and N.
]z O6ESH Note: The density function is zero unless X is an integer.
T)MX]T VTUSM{TC The size of Y is the common size of the input arguments. A scalar input
bMq)[8,N functions as a constant matrix of the same size as the other inputs.
j/t)=c IM$ d~C See also hygecdf, hygeinv, hygernd, hygestat, pdf.
s%QCd U ] |.z4 VJi4 Reference page in Help browser
`pb=y} doc hygepdf
cYgd 1 _z=yt t9D 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：
:: p%R@? ;il+C!6zpf http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m A("\m>g$b o2D;EUsNX 直到发现这个例子后才清楚各个参数所代表的具体意义。
uZM %F) <a&w$ Zc/ 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?
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* C{:U<q p = hygepdf(0:5,100,20,10)
llN / {%_D> y p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
m\oxS;fxWi ekW#| 详细可参见：
O7]kcA http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 mlYkn ce3 ``W/H3 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
2:@,~{`#* X$Shi
*U[ x = 0:5
75pn1*"gQ p = hygepdf(x,100,20,10);
EQe$~}[ plot(x,p,':k*')
