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
:?#wWF . n{c-3w.uD ans =
Mt12 1Q&" C\ cZ NaN
GMob&0l8_ T=pKen / 查看了一下帮助 help hygepdf
u)P)r, [{+ZQd HYGEPDF Hypergeometric probability density function.
2QIo|$ 3 +D4$Y" Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
S?~/
V ] density function at X with integer parameters M, K, and N.
+ j6^g* Note: The density function is zero unless X is an integer.
*AYjMCo tZD^<Q7}\ The size of Y is the common size of the input arguments. A scalar input
SR9M:%dga functions as a constant matrix of the same size as the other inputs.
o1<Z; 2 # |c,'0V,"cH See also hygecdf, hygeinv, hygernd, hygestat, pdf.
]=]`Mnuxb [>kzQY T[ Reference page in Help browser
CH=k=)() ] doc hygepdf
^c>ROpic `%0k\,}V 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：
O'W[/\A56M 8PW3x-+ http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m =,W~^<\" Y2y =
P 直到发现这个例子后才清楚各个参数所代表的具体意义。
mC`U"rlK~ _We4% 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?
BH?fFe&J:` 0 aiE 0b9c p = hygepdf(0:5,100,20,10)
_,|N`BBqd Cqw`K P p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
st(Y{Gs M4}zRr([.5 详细可参见：
7C^W <SUo http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 aw'o=/a8 x o(3<1mD 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
lO^YAOY yvKKE x = 0:5
.^?Z3iA", p = hygepdf(x,100,20,10);
T9P u V plot(x,p,':k*')
