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
v8 =#1YB; sj/k';#g ans =
!^MwE] mUP!jTF NaN
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Y1 @~ v 查看了一下帮助 help hygepdf
[c1Gq)ht #P}n+w_@ HYGEPDF Hypergeometric probability density function.
e&i`/ m5 JK!`uG+v Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
ESoC7d&.K{ density function at X with integer parameters M, K, and N.
7z3tDE[# Note: The density function is zero unless X is an integer.
sDg1nKw( LD?\gK " The size of Y is the common size of the input arguments. A scalar input
0 !%G #~th functions as a constant matrix of the same size as the other inputs.
Y{ dX[^[ hTEb?1CXU See also hygecdf, hygeinv, hygernd, hygestat, pdf.
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, Reference page in Help browser
uc"%uc' doc hygepdf
x5\D u63 fATVAv 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：
> fV "bj. P ei Re http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m ^.@%n1I"5y V+lS\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。
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= 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?
v8C( $<3% - "H$ &p~ p = hygepdf(0:5,100,20,10)
lcpiCZ 7;TMxO=bra p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
NA0Z~ Ug> b5%<},ySq 详细可参见：
u U q= L http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 C]JK'K<7- H2[0@|<< 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
9L-jlAo< M/[_~ x = 0:5
4/ *@cW p = hygepdf(x,100,20,10);
zXlerQWUv plot(x,p,':k*')
