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
5c9 ^-|-T tI]Q%S, ans =
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tG:25 T0 u&^b~# T 查看了一下帮助 help hygepdf
vhe>)h*B r~E=4 oB7 HYGEPDF Hypergeometric probability density function.
5:\},n+VE rr+|Zt
Y Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
R"4Vtww density function at X with integer parameters M, K, and N.
8H;t_B Note: The density function is zero unless X is an integer.
&[_g6OL R(! s The size of Y is the common size of the input arguments. A scalar input
3("_Z% functions as a constant matrix of the same size as the other inputs.
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1Dj2 @u.58H& }R See also hygecdf, hygeinv, hygernd, hygestat, pdf.
) dn( G@5 O80<Z#%j` Reference page in Help browser
^b/ Z)3 doc hygepdf
YO#M/%^j r/4``shg 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：
WM
Fb4SUR !_ "@^?,q http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m w&X<5'G M |) nZ^Cc 直到发现这个例子后才清楚各个参数所代表的具体意义。
M.Y~1c4f 3? [dE< 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?
'ZT^PV \ Di y8gt p = hygepdf(0:5,100,20,10)
wi;Br[d ? Fi=P# p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
e 63uLWDT #eQJEajv5 详细可参见：
zepm!JR1 http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 'GB. UKlR #J@[Wd 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
:S.9eFfa $Oq^jUJ x = 0:5
kr+D,h01 p = hygepdf(x,100,20,10);
,3?Q(=j plot(x,p,':k*')
