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
sjG@4Or !]l;n
Fd ans =
D),hSqJ" * \%b1 NaN
:[?65q{ i9 v|*ZM" 查看了一下帮助 help hygepdf
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+ HYGEPDF Hypergeometric probability density function.
36\_Y?zx % sDP8! Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
XU6SYC"t%~ density function at X with integer parameters M, K, and N.
8 ] &\FA 8 Note: The density function is zero unless X is an integer.
(\H^ KEy 9F2MCqvcm The size of Y is the common size of the input arguments. A scalar input
]:svR@E functions as a constant matrix of the same size as the other inputs.
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pDa See also hygecdf, hygeinv, hygernd, hygestat, pdf.
R/jHH{T 3 q" @%W K Reference page in Help browser
X.[8L^ldh doc hygepdf
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f %,f(jQfg_ 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：
aPm2\Sq$ PZk"! I<oN http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m
J7p?9 csj 4?]gI 直到发现这个例子后才清楚各个参数所代表的具体意义。
:|\)=4 ][B>`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?
a \tv,Lx yeI c Q% p = hygepdf(0:5,100,20,10)
="P&!lu $Go)Zs-bL? p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
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详细可参见：
&VT O9d http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 #Q$+ AdY| =`.OKU An 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>%mJ 3M ? u~?:a@K x = 0:5
cBQ+`DXn5c p = hygepdf(x,100,20,10);
MS;^@>|wj plot(x,p,':k*')
