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
s jm79/ N &=2 / ans =
-::%9D }P| "'Uk0>d=_I NaN
sdQv:nd'R c ? XUb[ 查看了一下帮助 help hygepdf
mNoqs&UB ,~(}lvqVH HYGEPDF Hypergeometric probability density function.
V sEAo Hw &M2a Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
^ {f ^WL= density function at X with integer parameters M, K, and N.
E e>j7k.G. Note: The density function is zero unless X is an integer.
Xf9%A2 iB (p=GR# The size of Y is the common size of the input arguments. A scalar input
vWs c{9 functions as a constant matrix of the same size as the other inputs.
!`o:+Gg@ {LHe 6# See also hygecdf, hygeinv, hygernd, hygestat, pdf.
X>7]g670@ 9'g{<(R] Reference page in Help browser
7"p s#)O doc hygepdf
<z 2mNq E2'e}RQ 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：
tY'QQN|| pVS2dwBqE http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m K- C-+RB yMl'1 W 直到发现这个例子后才清楚各个参数所代表的具体意义。
5C1Rub) L]N2r MM 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?
8p { @;D}=$x p = hygepdf(0:5,100,20,10)
6xh#;+e } -Jo :+]. p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
A 5<Z&Y[ h./vTNMc 详细可参见：
FNCLGAiZ http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 `yX+NRi(s '.
Hp*9R 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
% 3-\3qx* R+VLoz* J6 x = 0:5
8:?Q(M7 p = hygepdf(x,100,20,10);
vr ;Br-8 plot(x,p,':k*')
