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
uW;Uq=UN 5`oor86 ans =
Cd#*Wp )s vJ GxD\h NaN
i#lvt#2J0 PGT!HdX#{ 查看了一下帮助 help hygepdf
S rK;b . L3q)j\ ls HYGEPDF Hypergeometric probability density function.
e^~t52] 9 )B >|#\ Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
<!X'- >i%q density function at X with integer parameters M, K, and N.
F)e* w:D Note: The density function is zero unless X is an integer.
Djf2ir' o)}b Fw The size of Y is the common size of the input arguments. A scalar input
f;u;hQxs functions as a constant matrix of the same size as the other inputs.
WbH/K]/1)h % n}fk j' See also hygecdf, hygeinv, hygernd, hygestat, pdf.
a }E8A DyC l[G ,sq" Reference page in Help browser
nq/xD;q doc hygepdf
+6<M K; 3Un/-4uL 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：
JPQ02&e
4EB $e? http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m n4."}DO UMhM8m!=o 直到发现这个例子后才清楚各个参数所代表的具体意义。
6El%T]^ w#P aN83+ Suppose you have a lot of 100 floppy disks and you know that 20 of them are defective. What is the probability of drawing 0 through 5 defective floppy disks if you select 10 at random?
vW$] :). R~RY:[5?w p = hygepdf(0:5,100,20,10)
" "a+Nc 7C2/^x P p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
5tq$SF42X yvDzxu 详细可参见：
SVq7qc9K? http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 Ur&: Rr _%zU ^aE 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
i UI,r* y_ $^Po x = 0:5
* y(2BrL> p = hygepdf(x,100,20,10);
8-?n<h%8E plot(x,p,':k*')
