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 $ n
7dIE ^>k [T. ans = PlBT
H _W?}%; NaN K*CO%:,- jF-z? 查看了一下帮助 help hygepdf t;y>q N,Y<mX HYGEPDF Hypergeometric probability density function. z@<`] rxm!'.+ Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability Fwho.R-. density function at X with integer parameters M, K, and N. M@{GT/`Pf Note: The density function is zero unless X is an integer. MdEZ839J W13$-hf9 The size of Y is the common size of the input arguments. A scalar input SV8rZWJ functions as a constant matrix of the same size as the other inputs. mC J/gWDY *"1]NAz+ See also hygecdf, hygeinv, hygernd, hygestat, pdf. D!)'c(b =%$ _)=}J Reference page in Help browser SDdK5@1O4o doc hygepdf gD&%$&q R.>/%o 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: p,ZubRJ" [/5>)HK} C http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m {kW!|h&' J/RUKhs/ 直到发现这个例子后才清楚各个参数所代表的具体意义。 #2x\d b6);bX>e 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?
4[bw/[ f9OVylm p = hygepdf(0:5,100,20,10) c67O/ B( $@Hw DRP p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215 ,'82;oP4 CBi
V':; 详细可参见: %2/WyD$U http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 4S03W
#4d0/28b 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 #T
!YFMh; 7jEAhi!Cq( x = 0:5 1a#wUd3
p = hygepdf(x,100,20,10); Hhfqb"2on plot(x,p,':k*')
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