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
0E@*&Ru o76{;Bl\ O ans =
,Z8)DC= ROO@EQ#`Z NaN
VWk{?*Dp %kP=VUXj 查看了一下帮助 help hygepdf
]UGk"s5A {9cj itl HYGEPDF Hypergeometric probability density function.
w=5<mw P]2V~I/X Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
5!Ovd
O}g density function at X with integer parameters M, K, and N.
$M$-c{>s Note: The density function is zero unless X is an integer.
v z&88jt _
Ewkb The size of Y is the common size of the input arguments. A scalar input
O0eM*~zI functions as a constant matrix of the same size as the other inputs.
O .jCDAP x
}]"jj2x See also hygecdf, hygeinv, hygernd, hygestat, pdf.
| 3 `8$- wVc ^ l Reference page in Help browser
X3?RwN:P doc hygepdf
Mt@Ma ]! !.49 9H3 超几何分布参数较多，这里关于三个参数的指代不详。又在互联网上查了相关资料，包括该函数的定义式：
y~Mu~/s I ^[[*Bh*C http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m LG??Q+`l B` )bo}h 直到发现这个例子后才清楚各个参数所代表的具体意义。
gJ^taUE {vQ:4O!: Suppose you have a lot of 100 floppy disks and you know that 20 of them are defective. What is the probability of drawing 0 through 5 defective floppy disks if you select 10 at random?
Y+5aT(6O o.s(=iG p = hygepdf(0:5,100,20,10)
ZX'3qW^D 2WE01D9O p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
M
C y~~DL ^z51f>C 详细可参见：
rE0%R+4? http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 m|v$F,Lv 5<P6PHdY 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
b.RFvq5Z !lBK!'0 x = 0:5
=q*c}8R_0 p = hygepdf(x,100,20,10);
R \]C;@J< plot(x,p,':k*')
