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
:f1Q0klwP iBlZw%zKP ans =
/*,hR >UG Buazm3q8H NaN
9a4Xf%!F>z ME'hN->c 查看了一下帮助 help hygepdf
'#JC 6#X dS9L( & HYGEPDF Hypergeometric probability density function.
H<6TN^ .v<Q -P\8/ Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
~ti{na4W< density function at X with integer parameters M, K, and N.
f;"; P Note: The density function is zero unless X is an integer.
_G9 vsi @JFfyQ {- The size of Y is the common size of the input arguments. A scalar input
mR JX , functions as a constant matrix of the same size as the other inputs.
T_T@0`7 l]:nncpns See also hygecdf, hygeinv, hygernd, hygestat, pdf.
vd0;33$L zB,Vi-)vH Reference page in Help browser
u7L!&/ 6On doc hygepdf
T&@xgj|!) j A/xe 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：
=}SH*xi6 /da5 " http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m `R\aNgCS} {[Bo"a>% 直到发现这个例子后才清楚各个参数所代表的具体意义。
}r%S i A}. / ;[ 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?
AHa% ?wb 7t 8[M( p = hygepdf(0:5,100,20,10)
3}U {~l!K >b6 !*Lrhs p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
Ab|
t E5% TgFj- "L\ 详细可参见：
+@n8DM{b http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 bLSZ Zfq hT
c
VMc 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
6I5,PB km%c0: x = 0:5
PAYbsn p = hygepdf(x,100,20,10);
l'Oz-p.@ plot(x,p,':k*')
