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
*:9 > W$0u Er"R;l]xJ ans =
|,;twj[?4 W " "*hJ NaN
1xO!w+J# {jOzap| 查看了一下帮助 help hygepdf
Yz=h"Zr - J"qrpZ^ HYGEPDF Hypergeometric probability density function.
4<T*i{[ UU iNR Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
B;z;vrrL density function at X with integer parameters M, K, and N.
4D^ M<Xn Note: The density function is zero unless X is an integer.
5zNSEI"PY j?:`-\w5 The size of Y is the common size of the input arguments. A scalar input
| } K functions as a constant matrix of the same size as the other inputs.
5L Qk8NPh &
u$(NbK See also hygecdf, hygeinv, hygernd, hygestat, pdf.
C-llq`(d j)jCu ;` Reference page in Help browser
EKZA5J7kn doc hygepdf
iH-bo@ &Nc[$H7< 超几何分布参数较多，这里关于三个参数的指代不详。又在互联网上查了相关资料，包括该函数的定义式：
TC qkm^xv (y1$MYZ Q http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m >M?H79fF2s GI4?|@%vD! 直到发现这个例子后才清楚各个参数所代表的具体意义。
f:]u` ziM O\6vVM[ 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?
Bk,2WtVX r0>q%eM8 p = hygepdf(0:5,100,20,10)
.iFViVZC 8tU>DJ}0 p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
~?gzq~~t jDR')ascn 详细可参见：
2Kjrw; http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 @B?FE\ wHf&R3fg 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
jh[
#p?: AcKU^T+ x = 0:5
4sTMgBz w p = hygepdf(x,100,20,10);
vd`O aM}#U plot(x,p,':k*')
