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
s<Ex" + agU%z:M{ ans =
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DMAf^.,S Ei {( 查看了一下帮助 help hygepdf
YW?7*go'Z <}28=d HYGEPDF Hypergeometric probability density function.
Hi; K"H]x1 0a2 $P+p Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
_[}G(< density function at X with integer parameters M, K, and N.
fqcU5l[v, Note: The density function is zero unless X is an integer.
}t@f |TX lL:KaQ 0E The size of Y is the common size of the input arguments. A scalar input
)|U_Z"0H^ functions as a constant matrix of the same size as the other inputs.
Q^a&qYK BKE\SWu See also hygecdf, hygeinv, hygernd, hygestat, pdf.
CN\|_y C2+{U Reference page in Help browser
$i ,6B9 doc hygepdf
jzl?e[qPA pau*kMu^} 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：
8%;}LK Smq r
q http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m o,?!"*EP K-2.E 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*0:bhhhf_ $R A4U< Suppose you have a lot of 100 floppy disks and you know that 20 of them are defective. What is the probability of drawing 0 through 5 defective floppy disks if you select 10 at random?
]$m#1Kj Zg)_cRR p = hygepdf(0:5,100,20,10)
dV5PhP>6 DNm(:%)0 p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
q%OcLZ<, 6uu^A9x 详细可参见：
ad" 'O] http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 x`]Of r' ^~ Ekg:` 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
M0cd-Dn %*$5!; x = 0:5
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,Om8P p = hygepdf(x,100,20,10);
mSU@UD|' plot(x,p,':k*')
