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
KD, ^*FkkL (opROsFh ans =
NSMjr_ L;.VEz! NaN
ny!lj a5[ Zzw}sZ?8 查看了一下帮助 help hygepdf
d{iu+=NXz f"Z qA'KB# HYGEPDF Hypergeometric probability density function.
R\9>2*w CU#L *kz Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
~4MtD f density function at X with integer parameters M, K, and N.
(B>yaM#5 Note: The density function is zero unless X is an integer.
$n=W2WJ6f Vr&el The size of Y is the common size of the input arguments. A scalar input
h"VpQhi functions as a constant matrix of the same size as the other inputs.
T =eT^?v S 0R8'Y See also hygecdf, hygeinv, hygernd, hygestat, pdf.
mC*W2#1 pF %K&+~CJE Reference page in Help browser
/32Ta doc hygepdf
N<L$gw+)$D V9 +xL 1U# 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：
}
D/+< &57qjA ,8< http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m ;x!,g5q" q l1- 4n*fU 直到发现这个例子后才清楚各个参数所代表的具体意义。
qO:U]\P 1zb$5 {,| 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?
^Ei *M0fF `7u \
p = hygepdf(0:5,100,20,10)
S KB@ &%| xc {i p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
i>ESEmb- cOzg/~\1 详细可参见：
c^ ixdk http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 /p"U 0=N4O!X9 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
[b7it2`dl KW&nDu t x = 0:5
zrLhQ3V#> p = hygepdf(x,100,20,10);
T5 K-gz7A plot(x,p,':k*')
