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
9Tg IB N=4G=0 `ke ans =
^1S!F-H4\ y?[ v=j*U NaN
0[R L>;D: 4,bv)Im+ ` 查看了一下帮助 help hygepdf
54gBJEhg **w!CaqvY HYGEPDF Hypergeometric probability density function.
mC4zactv !POl;%\ Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
~ZmN44?R density function at X with integer parameters M, K, and N.
hEA<o67 Note: The density function is zero unless X is an integer.
chcbd
y>C gFeO }otm The size of Y is the common size of the input arguments. A scalar input
Vi>,kF.f V functions as a constant matrix of the same size as the other inputs.
8UXjm_B^ ' T}Km?d See also hygecdf, hygeinv, hygernd, hygestat, pdf.
lW+\j3?Z$ ZOft.P O Reference page in Help browser
%7"q"A r[ doc hygepdf
`_BNy=`s* |8&,b`Gfo 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：
X}=n:Ql'YY @G BxL*e http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m 3VsW@SG7N D8inB+ /- 直到发现这个例子后才清楚各个参数所代表的具体意义。
^W HE$4U` ~k \fhx 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?
T_s _p AJf4_+He p = hygepdf(0:5,100,20,10)
UR%/M V h hG4- HD p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
E=jNi ,p4&g)o 详细可参见：
DwaBdN[!7 http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 r;B8i !gD t|H^`Cv6 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
Q;[,Q~c[u & Lt}=3G x = 0:5
aUzBV\Yd} p = hygepdf(x,100,20,10);
'{a/2
l plot(x,p,':k*')
