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
~nrK>% BaSZ71>9]r ans =
SzjkI+-$: huJ&]"C NaN
.u4
W / :P<]+\m 查看了一下帮助 help hygepdf
ch 0{+g& #`o 2Z HYGEPDF Hypergeometric probability density function.
&Rvm>TC= [/Rf\T(,jn Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
,6om\9.E@ density function at X with integer parameters M, K, and N.
C}_ ojcR Note: The density function is zero unless X is an integer.
yn E)Xdh Q
aS\(_ The size of Y is the common size of the input arguments. A scalar input
MO n functions as a constant matrix of the same size as the other inputs.
a>GyO&+Dkg J[4mL U See also hygecdf, hygeinv, hygernd, hygestat, pdf.
mT.u0KUIy ApAO/q Reference page in Help browser
4scNSeW doc hygepdf
>[_f3;P \3pc "^W 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：
FQqI<6; eD*A ) http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m U-R6xxPZ maXG:l| 直到发现这个例子后才清楚各个参数所代表的具体意义。
q U]gj@R l]8D7(g 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?
`NgAT
3zq a=hxJ1O p = hygepdf(0:5,100,20,10)
X22[tqg;& U c@Ao: p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
QWz B6H] O"F_* 详细可参见：
J2 'Nd' http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 |Z=^`J [%77bv85.G 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
P] UJ0b (] Y 5eM x = 0:5
&NH$nY.r p = hygepdf(x,100,20,10);
xwJH(_- plot(x,p,':k*')
