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
[.}qi[=n c e;7 ans =
M/W"M9u z x-[@G NaN
@vl$[Z| u}%OC43 查看了一下帮助 help hygepdf
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% Hj' M {jXo%C HYGEPDF Hypergeometric probability density function.
rDWAZ<;; H\>{<`sD;f Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
$ )#orZtzr density function at X with integer parameters M, K, and N.
h?xgOb!4 Note: The density function is zero unless X is an integer.
u !BU^@ P 8Yq06o38C The size of Y is the common size of the input arguments. A scalar input
Jinh#iar functions as a constant matrix of the same size as the other inputs.
E*YmHJ:k (7g"pp f See also hygecdf, hygeinv, hygernd, hygestat, pdf.
_m9k2[N! '7'/ +G'~& Reference page in Help browser
{]dx Fhe) doc hygepdf
4;YP\{u TDo)8+.2 z 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：
'/I`dj d ~ M; http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m ?g ,s<{ Z,)H f 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+&~sX*a 6y^
zC? 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?
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p = hygepdf(0:5,100,20,10)
toY_1 @}q, ';H7 p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
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AOg '4 详细可参见：
*y4g\#o. http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 VZq CFE3 Ic&~iqQ 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
% G!!0V! hrKeOwKHU x = 0:5
G u `xJ p = hygepdf(x,100,20,10);
hF-Q bO plot(x,p,':k*')
