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
"MN' %"/ zvj >KF|y ans =
\ 2b9A' d> )Me&xQTn NaN
> `M\xt 0w]?yqnE 查看了一下帮助 help hygepdf
?[">%^ Q+dI,5YF HYGEPDF Hypergeometric probability density function.
df\>-Hl Z;:-8 HPDY Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
G_]mNh density function at X with integer parameters M, K, and N.
KS_d5NvYl Note: The density function is zero unless X is an integer.
EK^2 2vi$ 'r
CR8>k The size of Y is the common size of the input arguments. A scalar input
Q1yTDJ(2 functions as a constant matrix of the same size as the other inputs.
uy~j$ lrn *<1m
2t>. See also hygecdf, hygeinv, hygernd, hygestat, pdf.
~Ua0pS? R,lr&;a8 Reference page in Help browser
f Bmx +7 doc hygepdf
^
z;pP *XuzTGa" 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：
pppbn]%Ob C{-pVuhK+ http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m *h1@eJHMz zFI bCv8 直到发现这个例子后才清楚各个参数所代表的具体意义。
YeVhWPn@ :gXj( $ 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?
l_WY];a _C?K;-v} p = hygepdf(0:5,100,20,10)
bc -"If Z& 4p]Y`];U p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
K^+B" 4b)xW&K{ 详细可参见：
O`eNuQSv http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 9I9)5`d|Jn r *Mm5QozA 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
kDrGl{U}
@`T6\ 1 x = 0:5
P++gR@ p = hygepdf(x,100,20,10);
P?I"y,_ p plot(x,p,':k*')
