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
f fI=Bt]t FQ 0 ; %Z ans =
EqBTN07dZS W@z xGH$z> NaN
~Hd * Xl w87$p821 查看了一下帮助 help hygepdf
, ExY.'%1 sEK F HYGEPDF Hypergeometric probability density function.
rmC7!^ / |}8SjZcQW Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
pKLNBR| density function at X with integer parameters M, K, and N.
oV9{{ Note: The density function is zero unless X is an integer.
@o1#J` rv ?
47"$=G The size of Y is the common size of the input arguments. A scalar input
vqVwo\oEdU functions as a constant matrix of the same size as the other inputs.
;jQ^8 S j UZ$vyT See also hygecdf, hygeinv, hygernd, hygestat, pdf.
B@ z ng2[ OaT]2 o Reference page in Help browser
A|4
3W = doc hygepdf
(["V( $ T #:b 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：
uK#2vgT p Djt\R<f http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m 3A =\Mb eA``fpr 直到发现这个例子后才清楚各个参数所代表的具体意义。
-2u )orWP A@Zqh<,Ud 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?
8df| 9E$ b?!S$S xz p = hygepdf(0:5,100,20,10)
n
_x+xVi% *)?'! p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
" &`>+Yw '6g-]rE[ 详细可参见：
Y]`o- dV http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 92C; a5s 6f
t6;*, 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
.!+7|us8l\ k}qCkm27 x = 0:5
f<oU" WM p = hygepdf(x,100,20,10);
0` v-pL0| plot(x,p,':k*')
