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
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I,_wt+O&j BYqDC<Fq 查看了一下帮助 help hygepdf
4IG'T m cr27q6_ HYGEPDF Hypergeometric probability density function.
f)({;,q 1YTnOiYS1 Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
z5=&qo|f9l density function at X with integer parameters M, K, and N.
"qu% $L Note: The density function is zero unless X is an integer.
)^|zuYz N dp&4G6Y<A The size of Y is the common size of the input arguments. A scalar input
I o|NL6[ functions as a constant matrix of the same size as the other inputs.
sc@v\J;k Y@Lv>p See also hygecdf, hygeinv, hygernd, hygestat, pdf.
0N;Pb(%7UU INy reoMp Reference page in Help browser
|FS79 Bv doc hygepdf
Qx>S>f lo,?mj%M 超几何分布参数较多，这里关于三个参数的指代不详。又在互联网上查了相关资料，包括该函数的定义式：
E@}t1! E< 94 H\,}i 8 http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m vh"zYl` G;Q)A$- 直到发现这个例子后才清楚各个参数所代表的具体意义。
Y`uL4)hR5 gLaFIeF<+ 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?
*S~gF/*kP R.Ao%VT p = hygepdf(0:5,100,20,10)
B+ud-M0 c]P`U(q9TV p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
p,* rVz[Y |dsd5V dr 详细可参见：
/(bPc12 http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 . 8<bz4 ]uI#4t~ 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
SaH0YxnY+ S#/[>C b x = 0:5
;$ D*,W
* p = hygepdf(x,100,20,10);
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plot(x,p,':k*')
