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
MW{8VH6+ 4fzZ;2sl} ans =
}&e5$lB # [a*rD%m NaN
fT{Yg /j "\=U)C J 查看了一下帮助 help hygepdf
d7i]FV E E'!|N3 HYGEPDF Hypergeometric probability density function.
nOz.G" j=J/x:w_e Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
N&p Cx& density function at X with integer parameters M, K, and N.
,(4K4pN Note: The density function is zero unless X is an integer.
2 m[<]$ gNhQD*+>{ The size of Y is the common size of the input arguments. A scalar input
m 6djeOl functions as a constant matrix of the same size as the other inputs.
K@#L)VT! f9;(C4+ See also hygecdf, hygeinv, hygernd, hygestat, pdf.
@o6L6Y0Naa EZj9wd"u Reference page in Help browser
9C \Fq- doc hygepdf
:lzrgsW 0L KRN|@ 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：
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_l]fkk[T http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m -] =@s <|\Lm20 G] 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 {6a RGU\h[ 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?
N36_C;K-z |W\(kb+ p = hygepdf(0:5,100,20,10)
u4_9)P`]0 9 E6R0D} p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
+U.I( 83F "Yca%: 详细可参见：
w\brVnt http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 d: {O\ ujucZ9}y d 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
O#u=c1
?: ^ BL" wk x = 0:5
6(e>P) p = hygepdf(x,100,20,10);
PzR[KUK plot(x,p,':k*')
