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
PKtU:Eg \.>.c g ans =
Y$8; Gm<) AUAI3K? NaN
,RK3eQ qc0 B<,x7 查看了一下帮助 help hygepdf
)1_(>|@oi O_CT+Ou HYGEPDF Hypergeometric probability density function.
oeN zHp_ XV2=8#R Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
yisLypM* density function at X with integer parameters M, K, and N.
"|4jP za Note: The density function is zero unless X is an integer.
{,f[ r*{Y rbh[j@s@ The size of Y is the common size of the input arguments. A scalar input
]C)|+`XE@ functions as a constant matrix of the same size as the other inputs.
=h\E<d w uu3M{*} See also hygecdf, hygeinv, hygernd, hygestat, pdf.
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L Reference page in Help browser
X8b#[40: doc hygepdf
6F ;Or 0ny{)Sd6um 超几何分布参数较多，这里关于三个参数的指代不详。又在互联网上查了相关资料，包括该函数的定义式：
*aG"+c6| ~u2w`H?V http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m FQ## 3 97 )OUU ]MUH 直到发现这个例子后才清楚各个参数所代表的具体意义。
t&pGQ `e*61k5 Suppose you have a lot of 100 floppy disks and you know that 20 of them are defective. What is the probability of drawing 0 through 5 defective floppy disks if you select 10 at random?
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=} 7sguGwg) _ p = hygepdf(0:5,100,20,10)
N?^_= KE@ CXa Ld7nMX p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
96)v#B?p RO$*G
jQd 详细可参见：
@H4wHlb http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 {_Np<r;j< Loc8eToZ 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
) ]}$ y^YVo^3 x = 0:5
p |s2G~0< p = hygepdf(x,100,20,10);
?1$\pq^ plot(x,p,':k*')
