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
|#R7wnE[k~ a~y'RyA ans =
2.%ITB uiR8,H9*M NaN
w@w(-F!%l >7DhTM-A 查看了一下帮助 help hygepdf
}a(dy r`S z 1X` o HYGEPDF Hypergeometric probability density function.
A;?|& `f s&3Vg7B Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
suDQ ~\ n density function at X with integer parameters M, K, and N.
di )L[<$DY Note: The density function is zero unless X is an integer.
Em~>9f
?Q( SSMHo JGm The size of Y is the common size of the input arguments. A scalar input
oE]QF.n# functions as a constant matrix of the same size as the other inputs.
$kp{Eg ' ;vjOUn[E See also hygecdf, hygeinv, hygernd, hygestat, pdf.
_u QOHwn WX3-\Y5E Reference page in Help browser
tf`^v6 m%] doc hygepdf
Z=vU}S>r|v =]0&i]z[. 超几何分布参数较多，这里关于三个参数的指代不详。又在互联网上查了相关资料，包括该函数的定义式：
/hyN;.hpOO Zp=U
W*g^ http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m 3AN/
H j/?kL{B 直到发现这个例子后才清楚各个参数所代表的具体意义。
s|r3Gv|G PALc;"]O Suppose you have a lot of 100 floppy disks and you know that 20 of them are defective. What is the probability of drawing 0 through 5 defective floppy disks if you select 10 at random?
g e8ZsaiU 3L}A3de' p = hygepdf(0:5,100,20,10)
& 6nWzF T1=fNF p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
?m"( S oh sD#.Oq4&]y 详细可参见：
/h|#J http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 v):Or'$~M -PR N:'T 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
{F.[&/A >e$PP8&i_T x = 0:5
7WZ+T"O{I p = hygepdf(x,100,20,10);
ER.}CM6{[ plot(x,p,':k*')
