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
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U8,pe;/ln` (rq(y$N 查看了一下帮助 help hygepdf
mHH >qW{` 'tjqfR HYGEPDF Hypergeometric probability density function.
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1L X Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
T`]P5Bk8r density function at X with integer parameters M, K, and N.
dx$ +,R~y Note: The density function is zero unless X is an integer.
eF' l_ * [N<rPHT The size of Y is the common size of the input arguments. A scalar input
hf7[<I,jov functions as a constant matrix of the same size as the other inputs.
C \^,+)Y\~ IlB*JJ nl See also hygecdf, hygeinv, hygernd, hygestat, pdf.
X!@ Y , 7" )~JBH Reference page in Help browser
\: B))y?}d doc hygepdf
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}6 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：
0F
2p4!@W 8`90a\t 'Z http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m ,/!^ZS* p\.I P2+c 直到发现这个例子后才清楚各个参数所代表的具体意义。
*9EW &Ek \m:( '^\6o 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?
"^Y zHq6 k~fH:X~x p = hygepdf(0:5,100,20,10)
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p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
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u i)$<j!L 详细可参见：
K6|R ;r5e{ http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 n9R0f9:* /w2-Pgm-[\ 果然与一般对超几何分布公式字母惯常表示方式有所不同。尝试将上述分布作图如下
JY~CMR5#.O 9\0$YY% x = 0:5
imKMPO= p = hygepdf(x,100,20,10);
8Dn~U :F/? plot(x,p,':k*')
