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
;_SSR8uHv bK!h{ Rr ans =
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^- NaN
_BA; H+M l'q%bi=f 查看了一下帮助 help hygepdf
SF-E> s!XL yYGs] + HYGEPDF Hypergeometric probability density function.
W/\VpD) ?; P<Bx1H-z- Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
3QBzyJW f density function at X with integer parameters M, K, and N.
_ f ";zd Note: The density function is zero unless X is an integer.
awo' #Y2> AB\Ya4O"9 The size of Y is the common size of the input arguments. A scalar input
q++\< \2 functions as a constant matrix of the same size as the other inputs.
@*<0:Q|m *]HnF P See also hygecdf, hygeinv, hygernd, hygestat, pdf.
aL[6}U0 (} ?Xvy0/s5 Reference page in Help browser
>i*,6Psl[Z doc hygepdf
O6/ vFEB %m dtVQ@ 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：
n"RV!{& ssLswb http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m dq.U#Rhrx 17?YN< 直到发现这个例子后才清楚各个参数所代表的具体意义。
7^#f)Vp Z5(9=8hB/ 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?
}R 16WY_' Jn=;gtD- * p = hygepdf(0:5,100,20,10)
1|4,jm $ v.<mrI#? p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
oDu6W9 + V: L%GWU 详细可参见：
. ,z6a http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 1UJ rPM% aR6F%7gvz 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
5z 0VMt PlH~um[J x = 0:5
h-1?c\Qq: p = hygepdf(x,100,20,10);
T4wk$R
L plot(x,p,':k*')
