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
z!)@` ? u3IhB8' ans =
KuMH,rXF \Z-Fu=8J8^ NaN
2W;2._ "f u@2y4^ 查看了一下帮助 help hygepdf
% ejq|i7 &,$N|$yK}| HYGEPDF Hypergeometric probability density function.
~zQxfl/ ^_uCSA'X Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
p-,Bq!aG$ density function at X with integer parameters M, K, and N.
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hb Note: The density function is zero unless X is an integer.
@R ;&P R#5 U=[isi+7 The size of Y is the common size of the input arguments. A scalar input
}`]Et99Q5 functions as a constant matrix of the same size as the other inputs.
F:LrQu Am#Pa,g See also hygecdf, hygeinv, hygernd, hygestat, pdf.
euET)Ccq ^O&&QR H~w Reference page in Help browser
RJ dijj doc hygepdf
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E0oN ~{ '|G8yojz 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：
J#\oc@ [ic%ZoZ_ http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m 8I0G%hD u"DE? 直到发现这个例子后才清楚各个参数所代表的具体意义。
&a'LOq+r' c9+yU~( 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?
3]kN 9n{ [ZS.6{vr p = hygepdf(0:5,100,20,10)
~gg&G~ ET rv2;)3/* p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
imyfki $B Nf}i / 详细可参见：
T5wVJgN> http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 877Kv); T/jxsIt3 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
Op hD_^ sk@aOv'*( x = 0:5
As j<u!L p = hygepdf(x,100,20,10);
\ !IEZ plot(x,p,':k*')
