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
l~;H~h!h/ Tz4,lwuWX7 ans =
NeAkJG=< iZ<^p1i NaN
a|SgGtBtT4 15+>W4v 查看了一下帮助 help hygepdf
vH%AXz IA &PaqqU. HYGEPDF Hypergeometric probability density function.
lqn7$ {YC!pDG Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
k__i Jsk density function at X with integer parameters M, K, and N.
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ki$=}+ Note: The density function is zero unless X is an integer.
ye:pGa w +~?ze,Di The size of Y is the common size of the input arguments. A scalar input
U`N|pPe:w functions as a constant matrix of the same size as the other inputs.
(+6 8s9XS7 Ni#!C:q See also hygecdf, hygeinv, hygernd, hygestat, pdf.
g6{.C7m [bk2RaX:i Reference page in Help browser
v#0F1a?]D doc hygepdf
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`Rw y=g9 wO 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：
u.sF/T=6f {a^A -Xh[u http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m )b`Xc+{> 5Ds/^fA 直到发现这个例子后才清楚各个参数所代表的具体意义。
~T@t7Cg "X0"=1R~ 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?
lffp\v{ w 7[h_"@_A7 p = hygepdf(0:5,100,20,10)
T6m#sVq KY34Sc p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
sd9$4k" d0Xb?-
}3M 详细可参见：
%a=K:" oU[ http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 yI/2 e [ /_<`#?5T( 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
fZ 1v| }/&Q\Sc x = 0:5
!>fYD8Ft, p = hygepdf(x,100,20,10);
,Tc3koi plot(x,p,':k*')
