| 我是菜鸟 |
2008-10-27 15:59 |
Matlab中超几何分布作图介绍
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 ,p/b$d1p :?:j$
=nWN ans = ,b.4uJg' CAo )v,f NaN eE riv@v %[\Ft 查看了一下帮助 help hygepdf *_).UAP. E][{RTs HYGEPDF Hypergeometric probability density function. >2Qqa;nx| 5q_OuZ/6 Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability &fd4IO/O density function at X with integer parameters M, K, and N. 6nWx>R< Note: The density function is zero unless X is an integer. @aV~.!! D>7_P7]y The size of Y is the common size of the input arguments. A scalar input )Y,?r[4{ functions as a constant matrix of the same size as the other inputs. Va
|9)m zyp"*0zUr See also hygecdf, hygeinv, hygernd, hygestat, pdf. |gRgQGeB 2bn@:71` Reference page in Help browser % 6hw doc hygepdf IL6f~! ME10dr 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: `7qp\vYL mv%:[+! http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m ?.Yw%{?TG > v!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。 JJHvj=9'o Y\z\{JW 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? `w=H'"Zv `i)ePiE p = hygepdf(0:5,100,20,10) wh m tEY g\{! 21M p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215 b`W'M:$ ExP25T 详细可参见: |o=\9:wV http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 nC!^,c aCi^^}! 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 ~B*\k^t` 6p=x gk-q x = 0:5 ^RyTK|SQ p = hygepdf(x,100,20,10); E e\-q plot(x,p,':k*')
|
|