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
--c)!Vxzx \)aFYDq#\ ans =
[ws;|n h 3|)cT 1ej NaN
^HT vw ~]5 ~-%z:Re'_ 查看了一下帮助 help hygepdf
8-kR {9r pj3H4yCM: HYGEPDF Hypergeometric probability density function.
g OE ? meThjCC Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
~%
`hh9] density function at X with integer parameters M, K, and N.
e~,+rM Note: The density function is zero unless X is an integer.
P+_1*lOG a jM\\a? The size of Y is the common size of the input arguments. A scalar input
9j-;-`$S functions as a constant matrix of the same size as the other inputs.
Yb Z?["S& Z3u6m0! See also hygecdf, hygeinv, hygernd, hygestat, pdf.
A%&lW9z7 Zm6jF Reference page in Help browser
od,,2pwK+ doc hygepdf
.+u r+ " i auY?Cj'"fs 超几何分布参数较多，这里关于三个参数的指代不详。又在互联网上查了相关资料，包括该函数的定义式：
XC}2GHO< j9/iBK\Y http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m z`u$C+ Ov wk^$DM/KJ) 直到发现这个例子后才清楚各个参数所代表的具体意义。
: ?Z 9 wLE|J9t%Ea Suppose you have a lot of 100 floppy disks and you know that 20 of them are defective. What is the probability of drawing 0 through 5 defective floppy disks if you select 10 at random?
!V4 (- 8 %Br1b6 V p = hygepdf(0:5,100,20,10)
KxFA@3 )lU ocm p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
(58r9WhS 3fYfj 详细可参见：
}h3[QUVf% http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 or7l} X Y10 果然与一般对超几何分布公式字母惯常表示方式有所不同。尝试将上述分布作图如下
~0Zy$L/D :Z83*SPc x = 0:5
!<X/_+G \ p = hygepdf(x,100,20,10);
R.GDCGAL plot(x,p,':k*')
