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
Qkib;\2 f>5RAg ans =
yUW&Wgc=: JZ% F NaN
|3,V%>z W #L"5pRg 查看了一下帮助 help hygepdf
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/ HYGEPDF Hypergeometric probability density function.
?66(t YU=ZZEVi Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
`,Nn4 density function at X with integer parameters M, K, and N.
M#cr*% Note: The density function is zero unless X is an integer.
6lW Fx bh dT )KvqX The size of Y is the common size of the input arguments. A scalar input
k<| l \]w functions as a constant matrix of the same size as the other inputs.
V*zz-
2 _i daIL> c" See also hygecdf, hygeinv, hygernd, hygestat, pdf.
8KtgSash Mg QU6O< Reference page in Help browser
ewrWSffe doc hygepdf
MXF"F:-Kn b_jZL'en 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：
j 3MciQ` R5eB,FN http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m iEviH>b 5 UB$`;'|i 直到发现这个例子后才清楚各个参数所代表的具体意义。
Ke?gz:9j e4Ox`gLa*p 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?
E^ok` wfO ) , ]2`w&k p = hygepdf(0:5,100,20,10)
S[ ~O') = b<<5N s p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
T_x+sv=|X! d%lHa??/ h 详细可参见：
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?'^6Xh http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 V< vPF xC T 5azYdzJy 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
V`\f+Uu t\pK`DM-[ x = 0:5
v] T(z L| p = hygepdf(x,100,20,10);
=kb6xmB^t plot(x,p,':k*')
