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
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o,CA; _ h8#5vO2 查看了一下帮助 help hygepdf
W7TXI~7 ,a9D~i 9R HYGEPDF Hypergeometric probability density function.
esh$* )1 zr3q>]oma Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
k_K,J 6_) density function at X with integer parameters M, K, and N.
qu<B%v Note: The density function is zero unless X is an integer.
~}$\B^z+ 9Q C"Od9H The size of Y is the common size of the input arguments. A scalar input
O>SuZ>g+7 functions as a constant matrix of the same size as the other inputs.
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UW=: JtYY T/P B See also hygecdf, hygeinv, hygernd, hygestat, pdf.
95$pG/o S aR}\Up Reference page in Help browser
|{7e#ww] doc hygepdf
MK-a $~< RRS~ xOg 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：
Dm|gSv8d, ^e a RgNz http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m ` $.X [\*U %z-dM` i 直到发现这个例子后才清楚各个参数所代表的具体意义。
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Suppose you have a lot of 100 floppy disks and you know that 20 of them are defective. What is the probability of drawing 0 through 5 defective floppy disks if you select 10 at random?
HUU >hq9 4Q$j]U&b p = hygepdf(0:5,100,20,10)
& %N(kyp *=$[}!YG p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
|'U,/ eW%L$I 详细可参见：
_&; ZmNNhc http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 r~Y>+ln.
8qFUYZtY 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
>vD ['XN , <CNE>@-f x = 0:5
,_.@l+BM. p = hygepdf(x,100,20,10);
%r M-"6Q plot(x,p,':k*')
