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
tBSW |0 =l SNs ans =
v^P O|Z ?4uL-z](V NaN
sq]F;=[5 zeRyL3fnmb 查看了一下帮助 help hygepdf
}2oc#0 7:~_D7n HYGEPDF Hypergeometric probability density function.
0 {mex4 DNi+"[~&P Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
/Kbl%u density function at X with integer parameters M, K, and N.
!m$jk2< Note: The density function is zero unless X is an integer.
8k79&| <N @Gu!N8 The size of Y is the common size of the input arguments. A scalar input
fy$1YI>!Q functions as a constant matrix of the same size as the other inputs.
!9x} ? ubro 0F: See also hygecdf, hygeinv, hygernd, hygestat, pdf.
cC X*D_kCB rlD8D|ZG Reference page in Help browser
a{e4i t doc hygepdf
kVL .PY\K 2rMpgV5 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：
,?3G;- T C"<g http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m Ho%CDz
z 4+ig'
|o 直到发现这个例子后才清楚各个参数所代表的具体意义。
_B0L.eF D{!IW!w 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?
zreU')a Xr{v ~bf p = hygepdf(0:5,100,20,10)
n`KY9[0U= #;<Y[hR{P p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
=">NQ)98u g .\[o@H 详细可参见：
~s{$WL& http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 f!"w5qC^ 7o4\oRGV 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
fR|A(u#9 Ep}s}Stlr} x = 0:5
cNH7C"@GVu p = hygepdf(x,100,20,10);
g= rbPbu plot(x,p,':k*')
