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
okz]Qc>G }t\
10nQ ans =
Hq? & Qo w,Q)@] _ NaN
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查看了一下帮助 help hygepdf
N`HSE=u> y:.?5KsPI HYGEPDF Hypergeometric probability density function.
gK WzFnW 6}ftB mv Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
x9%-pl P density function at X with integer parameters M, K, and N.
j{)~Q D ? Note: The density function is zero unless X is an integer.
.Vmtx ;, rnk- The size of Y is the common size of the input arguments. A scalar input
&P q\cNYzW functions as a constant matrix of the same size as the other inputs.
=:gjz4}_8 |<rfvsQ. See also hygecdf, hygeinv, hygernd, hygestat, pdf.
_dr*`y Xi \-OC|\{32 Reference page in Help browser
&\k?xN doc hygepdf
7/?DP wbx p.C1 n h 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：
b/nOdFO@ wWTQ6~Y%d http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m EjSD4 y@3kU*-1 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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Rq! m :CTL)ad2 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?
f&c]LH _ ~ M*gsW$ p = hygepdf(0:5,100,20,10)
j&CZ=?K^c C`0%C7 p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
@+&'%1 /PqUXF 详细可参见：
W`x)=y]Z http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 uoCGSXsi SKR ;wu 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
=Z`0>R` <Oa9oM},d x = 0:5
t#5:\U5r. p = hygepdf(x,100,20,10);
G3dh M#! plot(x,p,':k*')
