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` '$ C;a@Jjor' ans =
e wB!IJxh u{bL-a8} NaN
?z"KnR+?Q }r2[!gGd%| 查看了一下帮助 help hygepdf
S;A)C`X& r(}nhU Q%E HYGEPDF Hypergeometric probability density function.
zfjTQMaxh +=8X8<Pu Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
kd;'}x=5yP density function at X with integer parameters M, K, and N.
B; -2$
77 Note: The density function is zero unless X is an integer.
=J@`0 H" (BERY The size of Y is the common size of the input arguments. A scalar input
+zRh
fIJHH functions as a constant matrix of the same size as the other inputs.
V2yveNz\7 ,w&:_ n See also hygecdf, hygeinv, hygernd, hygestat, pdf.
p\U*;'hv >;i\v7 Reference page in Help browser
Ny gI67 doc hygepdf
( L|} ` JJ l7JwSTW 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&Eat |5 xz l http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m \8"QvC ] n9 fk,3 直到发现这个例子后才清楚各个参数所代表的具体意义。
{ (\(m/!Z KtMbze 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?
M\yHUS6N <pOl[5v] p = hygepdf(0:5,100,20,10)
s#lto0b"8 5
R*lVUix p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
6s,2Ne VWa w4{ y "A 详细可参见：
<F=Dj*] http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 TmiWjQv` l(Cf7o! 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
\|Qb[{<:, + v[O x = 0:5
C6)R# p = hygepdf(x,100,20,10);
b}%g}L D plot(x,p,':k*')
