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
e71dNL'$ NUvHY: ans =
{"x>ewAf (X ?'}Ur NaN
3tZC&!x? 'q:t48& 查看了一下帮助 help hygepdf
QwaAGUA &~SPDiu.t HYGEPDF Hypergeometric probability density function.
MkCq$MA ^G~C#t^ Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
-3)]IA density function at X with integer parameters M, K, and N.
M ~uX!bDH Note: The density function is zero unless X is an integer.
P t)Ni U fz A/ The size of Y is the common size of the input arguments. A scalar input
2
u{"R functions as a constant matrix of the same size as the other inputs.
t;?TXA A x2M'!VK>n1 See also hygecdf, hygeinv, hygernd, hygestat, pdf.
"iC*Eoz#. e/{1u$ Reference page in Help browser
n:#gKR-J doc hygepdf
H1bPNt6 3 1l(_SD;90t 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：
hA0g'X2eC ha%3%O8Z http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m "kHQ}#6r TO|&}sDh 直到发现这个例子后才清楚各个参数所代表的具体意义。
=mq02C~y AusCU~ :> 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?
M2.Pf s wy1xZQ<5 p = hygepdf(0:5,100,20,10)
:k"VR,riF + frkC| . p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
f.~-31 _eE hIQ9 详细可参见：
kp4(_T7R http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 Rpi@^~aPE a IA9rn 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
%nmD >QCe Y@+e)p{ x = 0:5
,dG2[<?o p = hygepdf(x,100,20,10);
J=*X%^jX9Z plot(x,p,':k*')
