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
CF]#0*MI Y/]J0D ans =
b&P2VqYgl C:ntr=3J NaN
]zh6[0V7V of/'
9Tj 查看了一下帮助 help hygepdf
6 F; |x :RDQP HYGEPDF Hypergeometric probability density function.
>2ny/AK| bo[[<j!"I Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
`P jS density function at X with integer parameters M, K, and N.
T)mh Note: The density function is zero unless X is an integer.
7VW/v4n \me- #: Gu The size of Y is the common size of the input arguments. A scalar input
qF4=MQm\aE functions as a constant matrix of the same size as the other inputs.
,~>u<Wc!S d(F4-kBd See also hygecdf, hygeinv, hygernd, hygestat, pdf.
"O<TNSbrC }*,z~y}V#
Reference page in Help browser
N{?Qkkgx doc hygepdf
#C +7~ns' bYwe/ sR 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：
,B$e'KQ
fK NDl\SD http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m \:>eZl? `o6T)49 直到发现这个例子后才清楚各个参数所代表的具体意义。
B&?xq)%*# 4 IXa[xAm 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?
(``|5;T\ Oee>d < p = hygepdf(0:5,100,20,10)
ZG)6{WS 23'Ac,{ p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
v<E_n;@9k vg\fBHzn 详细可参见：
hD,@>ky http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 &?M'(` ~ Y*Y V/ E. 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
QA #Jx M [6WcH0/T x = 0:5
Pj kjUP p = hygepdf(x,100,20,10);
vnH[D)`@ plot(x,p,':k*')
