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
t+oJV+@ r&-m=Kk$ ans =
Bq/:Nd[y y A{ W NaN
b~dIk5>O L@=3dp!\Cu 查看了一下帮助 help hygepdf
p=/m IwGqf.!.> HYGEPDF Hypergeometric probability density function.
"CiTa>x m*e{\)rd# Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
9rh}1eo7 density function at X with integer parameters M, K, and N.
l
& Dxg Note: The density function is zero unless X is an integer.
B^).BQ rD>*j~_+P The size of Y is the common size of the input arguments. A scalar input
G0E1 21`h functions as a constant matrix of the same size as the other inputs.
*<1r3! $ d?.2Kg See also hygecdf, hygeinv, hygernd, hygestat, pdf.
4k ./(f2+ <dyewy*.L Reference page in Help browser
tabT0 doc hygepdf
8Sz})UZ 54zlnM$ 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：
! 8`3GX:B_ = k\ J< http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m tT d\| RK w$- 7O 直到发现这个例子后才清楚各个参数所代表的具体意义。
5nbEf9 & #^+DL]*l Suppose you have a lot of 100 floppy disks and you know that 20 of them are defective. What is the probability of drawing 0 through 5 defective floppy disks if you select 10 at random?
A'P(a` @{Gncy| p = hygepdf(0:5,100,20,10)
3Hf0MAt g^zs,4pPU< p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
&^ 4++ CdL< *AH 详细可参见：
HSq}7S&U http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 =B. F;4 0 ftH:r_"O# 果然与一般对超几何分布公式字母惯常表示方式有所不同。尝试将上述分布作图如下
TX ]qhPd_$?D' x = 0:5
+S Jd@y@fR p = hygepdf(x,100,20,10);
;# Q%j%J plot(x,p,':k*')
