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
PXb$]H V n<ZPWlJ ans =
y }odTeq u7!9H<{>P NaN
Zl9@E;|= w_(3{P[Iz 查看了一下帮助 help hygepdf
YFO{i -*q }|P3(* S HYGEPDF Hypergeometric probability density function.
x e`^)2z |YJ83nSO~ Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
_;1{feR_ density function at X with integer parameters M, K, and N.
i od%YjZu Note: The density function is zero unless X is an integer.
H71sxek3 k ka5=u The size of Y is the common size of the input arguments. A scalar input
Gt`7i ( functions as a constant matrix of the same size as the other inputs.
[xMa^A>p 6\4-I^=B See also hygecdf, hygeinv, hygernd, hygestat, pdf.
!U^{`V jp[ 0t <nH%N}^ Reference page in Help browser
y0 * rY doc hygepdf
X]0>0=^ 3A7774n=P 超几何分布参数较多，这里关于三个参数的指代不详。又在互联网上查了相关资料，包括该函数的定义式：
TQa}P s 6%v9o?:~l http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m 2xI |G
3U O viS(}v4@ 直到发现这个例子后才清楚各个参数所代表的具体意义。
u!_l/'\ V>{< pS Suppose you have a lot of 100 floppy disks and you know that 20 of them are defective. What is the probability of drawing 0 through 5 defective floppy disks if you select 10 at random?
.JhQxXj ht3.e[%'b p = hygepdf(0:5,100,20,10)
(f# (B2j ym%UuC3^w p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
P?54 "$b 22\!Z2@T/ 详细可参见：
AU{"G http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 ',+yD9 @ ,?fJ0n:!% 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
J!I) G&: k:@DK9
"^ x = 0:5
^Co-!jM p = hygepdf(x,100,20,10);
mB?x_6#d9 plot(x,p,':k*')
