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
w1G .^ ~ J{{n_G{ ans =
0qUap*fvC ABDUp: NaN
)t=u(:u] L=FvLii. 查看了一下帮助 help hygepdf
Y-{BY5E. "kg$s5o HYGEPDF Hypergeometric probability density function.
F}DD;K OIT;fKl9 Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
sYI':UQe density function at X with integer parameters M, K, and N.
W+S; Do Note: The density function is zero unless X is an integer.
-{%''(G .4(f0RG The size of Y is the common size of the input arguments. A scalar input
*?"{T;4u~O functions as a constant matrix of the same size as the other inputs.
kweTK]mT R u-rp^a See also hygecdf, hygeinv, hygernd, hygestat, pdf.
wKbymmG -y.AJ~ T Reference page in Help browser
]<LU NxBR doc hygepdf
!c($ C hyoZh Y 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：
BF!zfX?n N+75wtLy& http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m L:Eb(z/D lM"7 Z 直到发现这个例子后才清楚各个参数所代表的具体意义。
e_ -/p`9 mK4|=Q 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?
~]M" r/2:O92E p = hygepdf(0:5,100,20,10)
db~ :5#* /D+$|k mW] p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
)c !S@H s L|w-s4L 详细可参见：
S>E.*]_ http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 i8. [d5 b{Ss+F 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
]l%.X7M9 H-w|JH>g x = 0:5
Y
sV p = hygepdf(x,100,20,10);
RkwY3 s" plot(x,p,':k*')
