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
qKt8sxg \]GO*]CaV ans =
g]85[xz u':- DgK NaN
`bu3S }m7 _6" vPN 查看了一下帮助 help hygepdf
~R/w~Kc!/A 3 Yf%M66t HYGEPDF Hypergeometric probability density function.
sv\'Xa rM 21D4O,yCe Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
8( 3'YNC density function at X with integer parameters M, K, and N.
CN8Ge Z-G Note: The density function is zero unless X is an integer.
'c 5#M,G~ Ze ~$by|9f The size of Y is the common size of the input arguments. A scalar input
L,!?'.*/] functions as a constant matrix of the same size as the other inputs.
-q' n p0H UfjLNe}wA See also hygecdf, hygeinv, hygernd, hygestat, pdf.
:0IxnK(r& %F-/|x1#Q Reference page in Help browser
I7TdBe- doc hygepdf
{ 6Lkh A] R7H1 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：
SjD, !Sr^4R +Z http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m 3 lH#+@ Je_Hj9#M\d 直到发现这个例子后才清楚各个参数所代表的具体意义。
75i
M_e\ k1Zu&4C \ 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?
! P/ ]o S+H#^WSt p = hygepdf(0:5,100,20,10)
/+4Dq4{ t) 6-va;G9Fc p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
3Gq Js a
OR} 详细可参见：
VaC#9Tp2X http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 ~J?O ~p`& uA=6 HpDB 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
nV 38Mj2U %Y%+K5;AZ x = 0:5
nP?=uGqCBq p = hygepdf(x,100,20,10);
7Z5,(dH> plot(x,p,':k*')
