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
fmX!6Kv W ?woNt'n ans =
sD;M!K_ (Z] HX@"{J NaN
6%G-Vs]*2 <y. ]ImO 查看了一下帮助 help hygepdf
#W>QY Tp V)ig)(CT HYGEPDF Hypergeometric probability density function.
< A BX0U[* X{xBYZv4 Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
W/$ Zvl density function at X with integer parameters M, K, and N.
yLE7>48 Note: The density function is zero unless X is an integer.
942lSyi x Z @ dC+0[= The size of Y is the common size of the input arguments. A scalar input
SRIA*M.B} functions as a constant matrix of the same size as the other inputs.
2Os1 C}m j$7|XM6 See also hygecdf, hygeinv, hygernd, hygestat, pdf.
B;>{0
s ~^ jq(:d) Reference page in Help browser
tJViA`@x doc hygepdf
m0n)dje T;TA7{B 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：
Z<[<n0o1 bNs4 5hDP http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m <7SpEVQ x!L QxoNF 直到发现这个例子后才清楚各个参数所代表的具体意义。
a 8k; (/ `{k"8#4:qA 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?
Hb} X-6N W!Hm ~9fz p = hygepdf(0:5,100,20,10)
{9Y+.46S Dl( 3wgA p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
q;g>t5]a y;w x?1 ) 详细可参见：
C?v[Z]t http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 MTg:dR_ 9vUO *D 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
'm1N/)F ^z1&8k"[^ x = 0:5
X+L) -d p = hygepdf(x,100,20,10);
VVH.2&`I plot(x,p,':k*')
