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
5;{H &O9Q tmtT ( ans =
D~\$~&_]= [r[ =W! NaN
.?hP7;hhI )[|3ZP` 查看了一下帮助 help hygepdf
xagBORg+Bd h?azFA~ HYGEPDF Hypergeometric probability density function.
FJ6u.u Ny%(VI5: Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
:dqn h density function at X with integer parameters M, K, and N.
_:"<[ >9 Note: The density function is zero unless X is an integer.
v@d aT$9; The size of Y is the common size of the input arguments. A scalar input
0p\@!Z H functions as a constant matrix of the same size as the other inputs.
` 5C~ Ck|8qUz- See also hygecdf, hygeinv, hygernd, hygestat, pdf.
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RO~aD!N Reference page in Help browser
2]ape !( doc hygepdf
yT,.z 0 E}tqQ*u 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：
'^"6+ k 9,r rQ QD_ http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m h|"9 LU4a w&KK3*="" 直到发现这个例子后才清楚各个参数所代表的具体意义。
S9",d~EM #*(t d<Cp 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?
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6 M*O{f p = hygepdf(0:5,100,20,10)
n;T7= 1_" 6ZQwBS0Y p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
r|qp3x ~7zGI\= P@ 详细可参见：
Sh8"F@P8 http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 1cD ! :[ G JqJlgHe 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
jWE :ek* }dd8N5b x = 0:5
ZXuv CI p = hygepdf(x,100,20,10);
9*1,!%] plot(x,p,':k*')
