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
d:K\W[$Bz 1r $-U h ans =
KU` *LB: ?=&S?p)-< NaN
ur'<8pDb$ {P~rf&Ee 查看了一下帮助 help hygepdf
IV. })8 H2R3I<j HYGEPDF Hypergeometric probability density function.
#vV]nI<MF. uWdF7|PN7 Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
/v5A) A$7 density function at X with integer parameters M, K, and N.
vQi=13Pw Note: The density function is zero unless X is an integer.
eP>_Cr Jb ,k4pW&A The size of Y is the common size of the input arguments. A scalar input
L7 }nmP>aR functions as a constant matrix of the same size as the other inputs.
={P`Tve 0!dNW,NfJ See also hygecdf, hygeinv, hygernd, hygestat, pdf.
e3;D1@
J3
Q_ Reference page in Help browser
%`5 (SC]. doc hygepdf
4joE"H6 /&# y-D_ 超几何分布参数较多，这里关于三个参数的指代不详。又在互联网上查了相关资料，包括该函数的定义式：
Zc~7R`v7} IXa~,a H71 http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m ) >FAtE
p)/e;q^ 直到发现这个例子后才清楚各个参数所代表的具体意义。
4}; @QFT* = exCpW> Suppose you have a lot of 100 floppy disks and you know that 20 of them are defective. What is the probability of drawing 0 through 5 defective floppy disks if you select 10 at random?
jC>ZMy8U)4 ch0^g8@Q[ p = hygepdf(0:5,100,20,10)
F:ycV~bE >E J{ * p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
T/P\j0hR ?tjEXg>ny 详细可参见：
2w7$"N http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 E72N=7v" # 2_FM!e 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
d5gwc5X /C!~v!;e x = 0:5
w e a p = hygepdf(x,100,20,10);
-6- sI plot(x,p,':k*')
