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
:o8 |P X7AxI\h ans =
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#-`S 8)=(eI$ NaN
iw=e"6V %OB>FY:| 查看了一下帮助 help hygepdf
ZI;*X~h od 5nRb HYGEPDF Hypergeometric probability density function.
jex\ 5 F' OO{nF Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
mXyN{`q= density function at X with integer parameters M, K, and N.
s~2o<# Note: The density function is zero unless X is an integer.
t-o,iaPG3 h@\-] zN{ The size of Y is the common size of the input arguments. A scalar input
[Z"Z5e` functions as a constant matrix of the same size as the other inputs.
&M< "Fmn 88,hza`#V See also hygecdf, hygeinv, hygernd, hygestat, pdf.
3<"j/9;K' HR"clD\{Di Reference page in Help browser
2T)k-3 doc hygepdf
,[6Rmsk A[^#8evaK 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：
L. yM" +6$+] u] http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m A{J?I: v%AepK& 直到发现这个例子后才清楚各个参数所代表的具体意义。
M>Tg$^lm m"/..&'GC 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?
1fMV$T==K !j`<iPI7B p = hygepdf(0:5,100,20,10)
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^zNKgSQ p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
fdX|t "oz 0m]QQGvJ{ 详细可参见：
t0e5L{ QJ http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 Hzm_o>^KC ;I vv4u 果然与一般对超几何分布公式字母惯常表示方式有所不同。尝试将上述分布作图如下
A+8)VlE\ Zv!XNc!"$y x = 0:5
l7jen=(Zb; p = hygepdf(x,100,20,10);
\A01 1R & plot(x,p,':k*')
