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
P!k{u^$L x,V r=FB ans =
BDVtSs<7 6W
Ur QFK NaN
=tY T8Q;al QmIBaMI# 查看了一下帮助 help hygepdf
3;Fhg!Z O a[TMDU;(/4 HYGEPDF Hypergeometric probability density function.
Z/J y'$x &+R?_Ooibk Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
Aiea\j Bv density function at X with integer parameters M, K, and N.
L/^I*p , Note: The density function is zero unless X is an integer.
xId.GWY1 Y6d@h? ht The size of Y is the common size of the input arguments. A scalar input
#LOwGJ$yVz functions as a constant matrix of the same size as the other inputs.
bN@
l?w as=LIw}Q4 See also hygecdf, hygeinv, hygernd, hygestat, pdf.
4X|zmr:A t
|oR7qa{w Reference page in Help browser
;*&-C9b doc hygepdf
WjqO@]P6 Q NVa?'0"Y 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：
Sa5G.^ XI "
2Dngw http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m 0SPk|k r N }YkMJy 直到发现这个例子后才清楚各个参数所代表的具体意义。
X n\jO>[Ef 0qT%!ku& 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?
Ti&z1 _u lb1Xsgm{ p = hygepdf(0:5,100,20,10)
Om {'1 C"enpc_C/ p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
8-6L|#J# { FT qu. 详细可参见：
^zgo#J 5O http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 L&O wPd \5cpFj5% 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
{kAc(
Rzus NS x = 0:5
2dgd~
p = hygepdf(x,100,20,10);
.3!1` L3 plot(x,p,':k*')
