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
K^bzZa+a %-!ruc "} ans =
8 munw / w0l7N NaN
<Y9vc:S )=TD} Xb 查看了一下帮助 help hygepdf
@BWroNg{ qepsR/0M HYGEPDF Hypergeometric probability density function.
+v:t Xxcv 5.ug Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
It Gi2'} density function at X with integer parameters M, K, and N.
`T2RaWR4= Note: The density function is zero unless X is an integer.
ab8uY.j !={Z]J The size of Y is the common size of the input arguments. A scalar input
R,CFU l7Q functions as a constant matrix of the same size as the other inputs.
WmTSxneo dxbP'2~ See also hygecdf, hygeinv, hygernd, hygestat, pdf.
es@_6ol .@ u"r~5 Reference page in Help browser
\D(6t!Ox doc hygepdf
Uj&2'>MJ$ Z- ;<R$ 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：
/v"u4Ipj l-4T Tg http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m vt}+d
StUm Reca5r1O 直到发现这个例子后才清楚各个参数所代表的具体意义。
j(mbUB* #?.Yc%5B 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?
@Ong+^m|PC ~Twjc I */ p = hygepdf(0:5,100,20,10)
7Uvf XzDNC :U!kn b"/> p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
_#xS1sD [<P( S~J 详细可参见：
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http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 &3l g\&" -o*IJQ_ 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
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%sBU /,dcr* x = 0:5
[ mph iH/ p = hygepdf(x,100,20,10);
3 RG*:9 plot(x,p,':k*')
