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
rG%_O$_dO ' GO..m"G ans =
6Kc7@oO~ U`4Z j1y NaN
;+Kewi;< aRKG)0= 查看了一下帮助 help hygepdf
M@8 6u^80 8[p6C Jl) HYGEPDF Hypergeometric probability density function.
cG"<*Xi < I8>1RXz Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
W@}5e- q)O density function at X with integer parameters M, K, and N.
)bg,rES M Note: The density function is zero unless X is an integer.
juZ3"" Nfvg[c The size of Y is the common size of the input arguments. A scalar input
AiI# " functions as a constant matrix of the same size as the other inputs.
* Bz& @g2L=XF See also hygecdf, hygeinv, hygernd, hygestat, pdf.
'V{k$ }P2 AUpC HG7 Reference page in Help browser
JKbB, doc hygepdf
Mo=-P2)>lt U,(+rMeY0 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：
X~4:sJ\P= O|m -k0n http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m Nr+1N83S} @Ec9Do> 直到发现这个例子后才清楚各个参数所代表的具体意义。
6>A8#VT LA Vgf> 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?
"Y0[rSz,UW FaM~ 56Pa p = hygepdf(0:5,100,20,10)
O m~C0 J#WPXE+Ds p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
7FFYSv,[: {q4"x5| 详细可参见：
>>x V-1h: http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 =h!m/f^x #| Po&yu4R 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*i_- ;W) 2p ,6=8^v x = 0:5
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A\0 p = hygepdf(x,100,20,10);
\ 2b9A' d> plot(x,p,':k*')
