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
B;A< pNT r}4 ans =
wZs jbNf`K aJzyEb NaN
Htm;N2$d S] R.:T_% 查看了一下帮助 help hygepdf
@#>YU peZ'sZ 6 HYGEPDF Hypergeometric probability density function.
*JA0Vs 5 )~{8C: Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
l|S_10x5 density function at X with integer parameters M, K, and N.
,ieew` Note: The density function is zero unless X is an integer.
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Uno6 hbSXa' The size of Y is the common size of the input arguments. A scalar input
,c&%/"i:w functions as a constant matrix of the same size as the other inputs.
FwpTQix! Blox~=cW See also hygecdf, hygeinv, hygernd, hygestat, pdf.
3|
F\a|N mu m4Uj Reference page in Help browser
9!,f4&G` doc hygepdf
E wa/6=]LA C 5^9D 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：
mNPz%B }Sh3AH/ http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m Ol)M0u CTf39R|7_ 直到发现这个例子后才清楚各个参数所代表的具体意义。
@^t1 SP p 4v MjVbr 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?
jyFKO[s\X *Xk gwJq p = hygepdf(0:5,100,20,10)
5 gZ * KS R' X0' p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
gJJ BRn{MI |o#pd\ 详细可参见：
@0D http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 <.U(% `| iHk /#a 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
T1A/>\Ns suFO~/lRno x = 0:5
NI2-*G_M p = hygepdf(x,100,20,10);
|HQF qa < plot(x,p,':k*')
