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
9\JQ7 $B 0 1V^L} ans =
y_p.Gzy(^} 7Nzbz3 NaN
(MLwQ iop p H@]Y+W 查看了一下帮助 help hygepdf
:A 1: k*mt4~KLT8 HYGEPDF Hypergeometric probability density function.
@ FO) 0 c{3wk7 Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
)%d*3\Tsd density function at X with integer parameters M, K, and N.
Wb}c=hZv Note: The density function is zero unless X is an integer.
P"/ G 9$ qm>,o The size of Y is the common size of the input arguments. A scalar input
QXgE
dsw functions as a constant matrix of the same size as the other inputs.
Jl 3g{a t. ='/` !N See also hygecdf, hygeinv, hygernd, hygestat, pdf.
O m;&_!i /U&Opo
{aO Reference page in Help browser
#Lv2Zoi>G doc hygepdf
wMqX)}> F8:vDv 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：
Qv,"($n\ aE;le{|!({ http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m *t[. =_v I M-L'9 直到发现这个例子后才清楚各个参数所代表的具体意义。
/+Lfrt u! "t!2I 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?
VCXJwVb QnZcBXI8 p = hygepdf(0:5,100,20,10)
Q8!) !r% QUU;g 2k p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
:8CvRO*< s l]_M 详细可参见：
+ s- lCz http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 3|.um_ 0 stc9_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
s CR67/ N[<\>Ps|u x = 0:5
Vx~,Uex0+ p = hygepdf(x,100,20,10);
emCM\|NQg& plot(x,p,':k*')
