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
La9}JvQoX hk:>*B} ans =
"` `>ii =RD>#' sUK NaN
6',Hs l1'v`! 查看了一下帮助 help hygepdf
(?R!y - w)zJ $l HYGEPDF Hypergeometric probability density function.
rDbtT*vN {cOx0= Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
Q c&Y|]p" density function at X with integer parameters M, K, and N.
MQx1|>rG Note: The density function is zero unless X is an integer.
z{\tn.67 I8) D The size of Y is the common size of the input arguments. A scalar input
4jTO:aPh_ functions as a constant matrix of the same size as the other inputs.
CZ u=/8?
6A]I" E]5 See also hygecdf, hygeinv, hygernd, hygestat, pdf.
[O&}Qk J QnaXjW2 Reference page in Help browser
RIXeV*ix doc hygepdf
Q\kWQOB_ gs3(B/";c 超几何分布参数较多，这里关于三个参数的指代不详。又在互联网上查了相关资料，包括该函数的定义式：
ZwLr>?0$
p C 4 C / http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m E9j<+Ik s. Z{mnD6 直到发现这个例子后才清楚各个参数所代表的具体意义。
%|}*xMQ T%6JVFD 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?
bS~Y _]B \u [} p = hygepdf(0:5,100,20,10)
dX)a D
$m aH uMm& p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
*w(n% f Lg!E 详细可参见：
n8; p]{ http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 4>V@+#Ec5
b7\> = 果然与一般对超几何分布公式字母惯常表示方式有所不同。尝试将上述分布作图如下
y@I 9>}"y sYDav)L. x = 0:5
3 c6e$/ p = hygepdf(x,100,20,10);
n5UUoBv plot(x,p,':k*')
