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
^^%JoQ. C (G(^_6 ans =
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Zr =ib C
8N% X2R 查看了一下帮助 help hygepdf
)X/*($SuA z&O#v9.NE| HYGEPDF Hypergeometric probability density function.
w4UD/zO iHPUmTus-- Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
4Rx~s7l density function at X with integer parameters M, K, and N.
rn;<HT Note: The density function is zero unless X is an integer.
yE#g5V& >Iuzk1'S The size of Y is the common size of the input arguments. A scalar input
lr,q{; functions as a constant matrix of the same size as the other inputs.
I?B,sl_w 6
Ew@L<v See also hygecdf, hygeinv, hygernd, hygestat, pdf.
c S4DN `?l3Ct* Reference page in Help browser
?=<~^Lk doc hygepdf
7'z(~3D E, GN| l 超几何分布参数较多，这里关于三个参数的指代不详。又在互联网上查了相关资料，包括该函数的定义式：
!NTH.U :g P$ _&
http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m LT/mb2 vB.l0!c\e_ 直到发现这个例子后才清楚各个参数所代表的具体意义。
=J](.78 &:<, c12 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?
&= X.* H% H(b)aw^(% p = hygepdf(0:5,100,20,10)
*7ZtNo[+ dN< , %}R p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
>p0KFU }Al YNEY 详细可参见：
\8e2?(@"k http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 M%I@<~wl <YH=3[ 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
KF U%DU G ^ *0'\/N& x = 0:5
yrnv!moc%t p = hygepdf(x,100,20,10);
\9`#]#1bx5 plot(x,p,':k*')
