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
I$ R1#s c39j|/!;Y ans =
5KfrkZ dz^b(q NaN
9)8Cf% <( O c.fvP^ZD 查看了一下帮助 help hygepdf
R58NTPm 8A5/jqnqt HYGEPDF Hypergeometric probability density function.
/OYa1, %NfXe[T Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
5 dhy80|g] density function at X with integer parameters M, K, and N.
PD^G$LT Note: The density function is zero unless X is an integer.
'oK o F D.-G!0! The size of Y is the common size of the input arguments. A scalar input
1szObhN-l functions as a constant matrix of the same size as the other inputs.
`*elzW A*vuS Qt( See also hygecdf, hygeinv, hygernd, hygestat, pdf.
RO|8NC<oj MN8>I=p Reference page in Help browser
rd< 43 doc hygepdf
c1r+?q$f _n/73Oh 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：
^^zj4 }On? b;{"@b,Y http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m :<mJ RsDf "GR *d{ 直到发现这个例子后才清楚各个参数所代表的具体意义。
q)f_! N 4lWqQVx 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?
:p,|6~b$ V0rQtxE{F p = hygepdf(0:5,100,20,10)
I 44]W & 5eE\
X / p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
W~ 2,J4= gL-kI *Ra 详细可参见：
gS'7:UH, http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 /t<
& qH5nw}] 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
-KV,l y631;dU x = 0:5
h`n '{s p = hygepdf(x,100,20,10);
*oeXmY plot(x,p,':k*')
