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
h'x~"k1 o4;Nb|kk9+ ans =
j#f&!&G5<& ,no:6&# NaN
Fzs'@* JY+[ 查看了一下帮助 help hygepdf
DV\ei") eLny-.i ,7 HYGEPDF Hypergeometric probability density function.
2&fwr>!$ i 8Xz Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
e;5Lv9?C8 density function at X with integer parameters M, K, and N.
;NeP&)Td Note: The density function is zero unless X is an integer.
Vcq?>mH&T J#DcT@ The size of Y is the common size of the input arguments. A scalar input
v`BG 1&/| functions as a constant matrix of the same size as the other inputs.
QP%Fz#u` )^Pvm See also hygecdf, hygeinv, hygernd, hygestat, pdf.
J\'5CG l%(`<a]VIB Reference page in Help browser
Xh"iP % doc hygepdf
})lT fy %UQB?dkf$ 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：
}%ThnFFBw ON0+:`3\ http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m wPJRp]FA O + &
xb 直到发现这个例子后才清楚各个参数所代表的具体意义。
AsLjU#jn FT>~ES]cQd 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?
7$W;4!BN* d $rUxqB. p = hygepdf(0:5,100,20,10)
A9Wqz"[ ;Ph )BY< p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
/2Lo{v=0[ =awO63j> 详细可参见：
rDX'oP: http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 5MY}(w l\;mP.! 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
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}vc! kdh9ftm*\ x = 0:5
?s) sPM? p = hygepdf(x,100,20,10);
1 bZiPG{ plot(x,p,':k*')
