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
XoCC / D*F4it. ans =
- qy6Un+ B&.FO O NaN
w`i l=ZAC nx^]>w 查看了一下帮助 help hygepdf
Ie`13 L2 )Ib<F 7 v HYGEPDF Hypergeometric probability density function.
3+G@g#MY 'b#0t#|TM Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
]b%Hy density function at X with integer parameters M, K, and N.
75T7+:p Note: The density function is zero unless X is an integer.
@g$Gti <p\6AnkMr The size of Y is the common size of the input arguments. A scalar input
%y |)=cm[ functions as a constant matrix of the same size as the other inputs.
k=B] &F t $xY #: See also hygecdf, hygeinv, hygernd, hygestat, pdf.
_;~,Cgfi , 'ZD=4_ Reference page in Help browser
G_k~X" doc hygepdf
o (r\E0 I {6c2{@ 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：
pm\x~3 jHs LK, bO| http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m E gal4 HaYE9/xS 直到发现这个例子后才清楚各个参数所代表的具体意义。
"(3BvMA&!9 `> ?ra- 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?
b r^_'1 3&[>u;Bp p = hygepdf(0:5,100,20,10)
j|/]#@Yr ?}RSw l
p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
7A\~)U @ zSSB>D 详细可参见：
I-WhH>9 http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 H*Kj3NgY a e*M f7 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
\yd
s5g!: @:U+9[ x = 0:5
q*7zx_ o p = hygepdf(x,100,20,10);
%ix)8+Eb plot(x,p,':k*')
