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
v J\pR~? b7 !Qn} ans =
Vm(1G8 a BhM '@g* NaN
RY c!~Wh~Y Sp7ld 7c 查看了一下帮助 help hygepdf
(S xR`QP?, I4i2+
*l} HYGEPDF Hypergeometric probability density function.
Gp4A. \7 ;3\3q1oX Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
u}!@ ,/) density function at X with integer parameters M, K, and N.
si&S% 4( Note: The density function is zero unless X is an integer.
Zm=(+
f C OTp The size of Y is the common size of the input arguments. A scalar input
356>QW'm functions as a constant matrix of the same size as the other inputs.
{]E+~%Va FDVcow*] n See also hygecdf, hygeinv, hygernd, hygestat, pdf.
Jrg2/ee,* L:_bg8eD# Reference page in Help browser
Bn61AFy` doc hygepdf
9uRF nzJVx PQK(0iCo4 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：
]4R[<<hd A|L 8P http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m QmLF[\Oo_ F1jglH/MF) 直到发现这个例子后才清楚各个参数所代表的具体意义。
GP&vLt51 /e]'u&a 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?
DyeQJ7p v2H#=E4cZ# p = hygepdf(0:5,100,20,10)
C8 vOE`U,J ]UH`Pdlt p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
fv`O4 ,y+ $cM( 详细可参见：
ccLq+a| http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 C?i >.t d}JP!xf% 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
K4]g[z -O&CI) `;B x = 0:5
+)j 1.X p = hygepdf(x,100,20,10);
9lGOWRxR) plot(x,p,':k*')
