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
2j*;1 @
W[LA< ans =
SkU'JM7<95 * c 9/ I NaN
Kw_> X&GcJ qD0s D2 x 查看了一下帮助 help hygepdf
p}I ,!~}
rXgU*3 RG HYGEPDF Hypergeometric probability density function.
& iYy \-i5b Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
4AA3D!$ density function at X with integer parameters M, K, and N.
:.u[^_
Note: The density function is zero unless X is an integer.
2GkJ7 cL oS.fy31p The size of Y is the common size of the input arguments. A scalar input
N{rC#A3 functions as a constant matrix of the same size as the other inputs.
& ZmWR ~
A? See also hygecdf, hygeinv, hygernd, hygestat, pdf.
MhT.Zg\ St 4YNS.| Reference page in Help browser
nZ7FG doc hygepdf
8y:c3j zP_ E 3%:7MB 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：
Bg3`w__l; I#?NxP\S http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m 0 H;,~
WY >Z-f</v03 直到发现这个例子后才清楚各个参数所代表的具体意义。
n ^kszIu~ "'i" @CR 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?
uj
6dP &\[3m^ L p = hygepdf(0:5,100,20,10)
>d1gVBhk k(As^'> p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
3"9'MDKH 'Ll,HgU; 详细可参见：
q4Z9;^S http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 +T\c <lJ9 [
QHSCF5 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
^
hoz<Ns Dl/Jlsd@ x = 0:5
.@7J8F S* p = hygepdf(x,100,20,10);
!w+A3Z>V plot(x,p,':k*')
