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
RC7]'4o H4&lb} ans =
pZqq]mHK \Je0CD=e` NaN
A>o *t=5 o$ jLzE" 查看了一下帮助 help hygepdf
QI'Oz{vE E yJJ0 HYGEPDF Hypergeometric probability density function.
z [L8$7L <lx+/o Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
e D?tLj density function at X with integer parameters M, K, and N.
1WxK#c-) Note: The density function is zero unless X is an integer.
< $lCkSx<Q
_=F=`xu The size of Y is the common size of the input arguments. A scalar input
X86O lP)eX functions as a constant matrix of the same size as the other inputs.
N8F~8lTi 96( v See also hygecdf, hygeinv, hygernd, hygestat, pdf.
Hq:X{)" I9_RlAd Reference page in Help browser
s >7}zU] doc hygepdf
gmw|H?] ]%@M>?Ywc 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：
S"NqM[ W Yvw(t j5_5 http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m EE&K0<?T|: [%y';`( x 直到发现这个例子后才清楚各个参数所代表的具体意义。
!Xf5e*1IS .sha& 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?
K X ,S f-vCm 5f p = hygepdf(0:5,100,20,10)
PUT=C1,OFR JjtNP)W e p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
h7G"G" *+Ek0M 详细可参见：
9-&Ttbb4)0 http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 >JHryS.j$4 81? hY4 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
w'Y7Il C \)#kquH/l x = 0:5
P+@/O p = hygepdf(x,100,20,10);
5sj4;w [ plot(x,p,':k*')
