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
8PQ& 7o x>K em$z ans =
_LK(j;6K} @`3)?J [w NaN
`]Xb w^Y'x SWu=n1J.?H 查看了一下帮助 help hygepdf
4-o$OI> #Rs7Ieu+ HYGEPDF Hypergeometric probability density function.
n V<YwqK ]ba<4: [Go Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
82$^pg> density function at X with integer parameters M, K, and N.
i9\Pks#l% Note: The density function is zero unless X is an integer.
R_lNC]b0 FKaY w The size of Y is the common size of the input arguments. A scalar input
q>Y_I<;'g functions as a constant matrix of the same size as the other inputs.
umi# Se3& xKx WtZ0 See also hygecdf, hygeinv, hygernd, hygestat, pdf.
(GZm+? :ZUy(8%Wl Reference page in Help browser
`VH m,g2 doc hygepdf
' =oV Jyd%!v 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：
d{0>R{uac X:DHz0S http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m ,[A} 86 iVFn t! 直到发现这个例子后才清楚各个参数所代表的具体意义。
sh0O~%]g %j=7e@ 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?
+q3W t| {MIs%w.G p = hygepdf(0:5,100,20,10)
NY_Oo!)3 S"lcePN p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
cewQQ& M+Dkn3bx 详细可参见：
?&?y-&. 5- http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 2WKA] l; k|w6&k3 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
fd(>[RP? k(s3~ S2h x = 0:5
JAgec` T% p = hygepdf(x,100,20,10);
r!(~Y
A plot(x,p,':k*')
