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
COi15( G2 .]9`eGVWj ans =
fWP]{z ` 9G6)ja?W NaN
TF%n1H-sF VnuG^)S 查看了一下帮助 help hygepdf
-O} )Y>=} |\bNFnn( HYGEPDF Hypergeometric probability density function.
hu-]SGb6 x ]VycS Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
MpKXC density function at X with integer parameters M, K, and N.
F%L"Q>aHW Note: The density function is zero unless X is an integer.
^|/< e?~I ;apLMMsWC The size of Y is the common size of the input arguments. A scalar input
s.(.OXD& functions as a constant matrix of the same size as the other inputs.
f}dlQkZ( [w](x See also hygecdf, hygeinv, hygernd, hygestat, pdf.
( w4XqVT <B%wq>4S Reference page in Help browser
c | %5SA doc hygepdf
kwi$ % Md X4Rp' 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：
6I[*p0j5 n6[shXH http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m <\*)YKjn/@ 7L+Wj }m 直到发现这个例子后才清楚各个参数所代表的具体意义。
+@$VJM%^7b 7]@M 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?
~ vP_c(8f C,;?`3bH@ p = hygepdf(0:5,100,20,10)
D ~inR3(} Gb2|e.z p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
t:dvgRJt* :qS~"@ ?< 详细可参见：
d% @0xsU1 http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 0MT?}D&TL yI =nu53BV 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
*K>2B99TXu ko.% @Y(= x = 0:5
H94_a e p = hygepdf(x,100,20,10);
[YQtX_ ;w plot(x,p,':k*')
