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
qR>"r"Fq %$3)xtS6 ans =
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$Eh8s( q7-.-k<dQ 查看了一下帮助 help hygepdf
ye^l~ mO~A}/je HYGEPDF Hypergeometric probability density function.
25-5X3(>j= LI/;`Y= Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
Ej7>ywlW density function at X with integer parameters M, K, and N.
_5l3e7YN Note: The density function is zero unless X is an integer.
yG%<LP2p@f &
~*qTojj The size of Y is the common size of the input arguments. A scalar input
szG 0?e functions as a constant matrix of the same size as the other inputs.
MRZ/%OZ. kIlK"= See also hygecdf, hygeinv, hygernd, hygestat, pdf.
[ta3sEPjs S`v+rQjW Reference page in Help browser
I,0Z* rw doc hygepdf
yDn8{uI {24Y1ohK 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:
cV+x.)a. N-9qNLSP http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m n>-"\cjV L^Q q[> 直到发现这个例子后才清楚各个参数所代表的具体意义。
5J 0Sc ZUiInO 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?
2B<0|EGtzw Y#[>j4<T p = hygepdf(0:5,100,20,10)
xO nW~Z Z.v2!u p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
<z+b88D z')zVoW, 详细可参见:
;{e=Iz}/ http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 ))z1T 8 K,o@~fj 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
TA~YCj$ Js("H x = 0:5
2-#:Y
p = hygepdf(x,100,20,10);
LNR~F_64Q plot(x,p,':k*')