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
J7+w4q~cB` f.6~x$:)`E ans =
+L%IG X2yTlLdY NaN
lAi2,bz" rHz||jjU 查看了一下帮助 help hygepdf
_}gtcyx ig+4S[L~n HYGEPDF Hypergeometric probability density function.
d@ J a}` N#ioJ^}n: Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
c#cx>wq9 density function at X with integer parameters M, K, and N.
'V&Y[7Aeq Note: The density function is zero unless X is an integer.
ig!7BxM)<h L'Q<>{;Ig The size of Y is the common size of the input arguments. A scalar input
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xq%?b functions as a constant matrix of the same size as the other inputs.
dl~|Izm -e]7n*}H$ See also hygecdf, hygeinv, hygernd, hygestat, pdf.
'0Q , iG<Som Reference page in Help browser
ytA WOt}` doc hygepdf
7cTk@Gq H/fUM 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：
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*[Q\ @)6jE !LC http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m #&
?g %' '{b1!nC; 直到发现这个例子后才清楚各个参数所代表的具体意义。
=E*G b[r_7 |j~lkzPnV 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?
5&!c7$K0 $XnPwOj p = hygepdf(0:5,100,20,10)
s1j{x&OSq t18$x "\4k p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
+^|iZbZKx #UP~iHbt\ 详细可参见：
%; "@Ah http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 En VuD
9 <wd]D@l7r 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
~+6Vdx m )Kd%\P P x = 0:5
6<76H p = hygepdf(x,100,20,10);
w3T ]H _V plot(x,p,':k*')
