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
E5$Fhc 43}uW, P ans =
/HE{8b7n3F u}">b+{! NaN
!gm@QO cF i*]$_\yl" 查看了一下帮助 help hygepdf
ZBk br S"cim\9xP HYGEPDF Hypergeometric probability density function.
Ihd{ tmr< nb\pB l Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
F-X L density function at X with integer parameters M, K, and N.
TFNB %| Note: The density function is zero unless X is an integer.
7Y%Si5 h:AB`E1 The size of Y is the common size of the input arguments. A scalar input
/ M@[ 8 functions as a constant matrix of the same size as the other inputs.
*=}\cw\A ei82pLM
z See also hygecdf, hygeinv, hygernd, hygestat, pdf.
^H!45ph?Jc K8Jsh F Ie Reference page in Help browser
g5 ;Ig doc hygepdf
w.(?O; ;lQ>>[* 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：
M1q_gHA #Ibpf , http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m 7.*Mmx ~]= d3 ]<'B:nb 直到发现这个例子后才清楚各个参数所代表的具体意义。
z?Cez*.h> (@Kc(>(: Y 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?
1=_Qj }!1 Eq=j+ch7 p = hygepdf(0:5,100,20,10)
FOAXm4" %l3f . p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
/?1^&a _/J`v`}G 详细可参见：
Ltk-1zhI http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 6@ ;sOiN+ vO)]~AiB 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
IAJ+n0U cAn_:^ x = 0:5
^x2@KMKXZ p = hygepdf(x,100,20,10);
oL7F^34; plot(x,p,':k*')
