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
. Um%6a- p
go\(K0 ans =
(Fgt #H(B X)f"`$ NaN
OEwfNZQ- M9OFK\) 查看了一下帮助 help hygepdf
LMG\jc?, lIFU7g HYGEPDF Hypergeometric probability density function.
4QZy-a*tA Gj_b GqF8} Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
Ju9v n44 density function at X with integer parameters M, K, and N.
wbS++cF< Note: The density function is zero unless X is an integer.
YKc{P"'/ | eu: _ V+ The size of Y is the common size of the input arguments. A scalar input
N~ozyIP, functions as a constant matrix of the same size as the other inputs.
+tN-X'u## `A^} X See also hygecdf, hygeinv, hygernd, hygestat, pdf.
YYvs~?bAy z"O-d<U5 Reference page in Help browser
M{4_BQ4 $ doc hygepdf
]Oj t3) fB x+TNF>%' D 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：
hW+Dko(s j5)qF1W, http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m v1lj /A z*[Z: 直到发现这个例子后才清楚各个参数所代表的具体意义。
5UM [Iz N+V-V-PVk 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?
D JW1kR E0pQRGPA p = hygepdf(0:5,100,20,10)
|5/[0V-vy d#tUG~jc p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
(o s7Q? KE3v3g< 详细可参见：
O&s6blD11 http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 an2Tc*=~l( M vh_>-i 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
4>E2G: By_Ui6:D x = 0:5
[Bh]\I' p = hygepdf(x,100,20,10);
Z 7/dRc
plot(x,p,':k*')
