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
;>EM[u h6D<go-b56 ans =
en4k/w_ 3=P]x ;[ba NaN
zII|9y +K:Dx!9 查看了一下帮助 help hygepdf
B
dj!ia;H YW,tCtI0_ HYGEPDF Hypergeometric probability density function.
n`?aC|P2s ;40/yl3r3[ Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
r"3=44St density function at X with integer parameters M, K, and N.
~zJbK. _ Note: The density function is zero unless X is an integer.
:1. L}4"gg Y1W1=Uc uk The size of Y is the common size of the input arguments. A scalar input
.nf#c.DI functions as a constant matrix of the same size as the other inputs.
1Ti f{i,B G#q@v (_b See also hygecdf, hygeinv, hygernd, hygestat, pdf.
L2[($ l YN yk1cE Reference page in Help browser
I#Y22&G1 doc hygepdf
hP%M?M KC ?|\ ER#z 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：
oQ/E}Zk@ Tj` ,Z5vy http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m 5FPM`hLT F `9xVnK= 直到发现这个例子后才清楚各个参数所代表的具体意义。
:\ `o8` #>("CAB02T 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?
b;B%q$sntC iJI }TVep# p = hygepdf(0:5,100,20,10)
lV3x *4O= $t'MSlF p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
\j}ZB<.> d`=MgHz 详细可参见：
^qvZXb http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 7FP*oN? Tt`u:ZwhF 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
~f&E7su-6+ 1Z /(G1 x = 0:5
J\} twYty p = hygepdf(x,100,20,10);
e }?d b plot(x,p,':k*')
