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
Vo9F d{3@h +zL ans =
v?0r`<Mn 7}GK%H-u NaN
`C_jP|[e j,t#B"hOnp 查看了一下帮助 help hygepdf
Yz4_vePh+5 &O)&k HYGEPDF Hypergeometric probability density function.
:LWn<,4F& E]J:~H'Er Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
^A][)* SZ density function at X with integer parameters M, K, and N.
rUlS'L;$" Note: The density function is zero unless X is an integer.
t4q ej X*g(q0N<S The size of Y is the common size of the input arguments. A scalar input
r rnNn' functions as a constant matrix of the same size as the other inputs.
xy8#2 /Y&02L%\3s See also hygecdf, hygeinv, hygernd, hygestat, pdf.
$55U+) C< GyW.2 Reference page in Help browser
) jCo%P/ doc hygepdf
D?~8za`5 )-Ej5'iHr 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：
sow d`I~ 9Ew7A(BG_3 http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m 4g}FB+[u /({;0I*!i 直到发现这个例子后才清楚各个参数所代表的具体意义。
!@I}mQ ~ t p:\j@dB 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?
ZUp\Ep} 6 CC &Z> p = hygepdf(0:5,100,20,10)
MlJVeo d ;' nL:\ p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
vBvNu<v7te ~gI{\iNF/ 详细可参见：
p0{EQT`tMG http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 Sf/q2/r?6[ 1z*kc)=JF8 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
Bi~:>X\[^6 P F`rWw x = 0:5
:Pq., s p = hygepdf(x,100,20,10);
Fl{ WAg plot(x,p,':k*')
