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
C5eol & K[ylyQ1 ans =
QJ$]~)w?H \f+R! NaN
B$7lL ag] nVE/ 查看了一下帮助 help hygepdf
wv1?v_4 <,LeFy\zW HYGEPDF Hypergeometric probability density function.
! D z:6r <q_H 3| Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
z9VQsC' K density function at X with integer parameters M, K, and N.
3 Hq0\Y"Y Note: The density function is zero unless X is an integer.
H-I*; IQH;`+ The size of Y is the common size of the input arguments. A scalar input
ma-|L3 # functions as a constant matrix of the same size as the other inputs.
f(9w FT ~kYF/B2* See also hygecdf, hygeinv, hygernd, hygestat, pdf.
z muq4-. hz Ppw. Reference page in Help browser
2!jbaSH(+ doc hygepdf
C@KYg/nYw Bw{W -&$o 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; yhL 8y+Gvk: http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m }}ogdq @GGyiK@ 直到发现这个例子后才清楚各个参数所代表的具体意义。
fF>H7 dkCSqNFL) 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?
8l?]UFM>C T nPC\ .x p = hygepdf(0:5,100,20,10)
:S,#*rPKBK Wqy8ZgSC p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
N["(ZSS =lVfrna 详细可参见：
OY?uqP}c http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 qHv W{0E 1AhL-Lj 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
J\2F%kBej? HI:E&20y x = 0:5
W[YcYa_tQ p = hygepdf(x,100,20,10);
D@\97t+ plot(x,p,':k*')
