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
WzlC*iv =2 jhII ans =
vVVPw?Ww- $f -hUOuyo NaN
O# _x)13 Kf.T\V4% 查看了一下帮助 help hygepdf
5 Op_*N{V MCYl{u H! HYGEPDF Hypergeometric probability density function.
]P1YHw9 )#[|hb=o Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
r<yhI>>;< density function at X with integer parameters M, K, and N.
Ade }g' Note: The density function is zero unless X is an integer.
?L|yaC~ 8^ #mvHah The size of Y is the common size of the input arguments. A scalar input
J@#?@0]F functions as a constant matrix of the same size as the other inputs.
]WL| ~mG fRHKQ(a# See also hygecdf, hygeinv, hygernd, hygestat, pdf.
KoHGweKl# Ai kf|)D[ Reference page in Help browser
= `t^~.5 doc hygepdf
LmL Gki$w ]gP5f @` 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：
JN[0L : PT]GJ<K/ http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m *g$i5!yM' ZGz| m0b ( 直到发现这个例子后才清楚各个参数所代表的具体意义。
(S9 f/i ^ ,XB%\[pKe 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?
jk7 0u[\ 7"Mk+' p = hygepdf(0:5,100,20,10)
7%d8D>uw8 ^T079=$5 p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
8 ws$k\> f
j<H6|3 详细可参见：
Ge \["`;i http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 $3;Up gv I/uy>* 果然与一般对超几何分布公式字母惯常表示方式有所不同。尝试将上述分布作图如下
!I8f#'p I1=(. *B} x = 0:5
j43$]'- p = hygepdf(x,100,20,10);
=8 JB8ZFP plot(x,p,':k*')
