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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UWkb Vp ] D ans =
C3\E.u ? G =Hf&l NaN
M6jp1:ZH2q * K,hrpYR 查看了一下帮助 help hygepdf
Z<ajET`) IObx^N_K HYGEPDF Hypergeometric probability density function.
)W1(tEq59 Cl6m$YUt Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
@1qdd~B} density function at X with integer parameters M, K, and N.
.5Knb c Note: The density function is zero unless X is an integer.
7 Y32p' (/SGT$#8 The size of Y is the common size of the input arguments. A scalar input
f{igW?Ho functions as a constant matrix of the same size as the other inputs.
OpK. Lsd0y %-#
q O See also hygecdf, hygeinv, hygernd, hygestat, pdf.
ZM oJ#p( eB= v~I3 Reference page in Help browser
os1?6 z~ doc hygepdf
WDE e$k4. !6zyJc @01 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：
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j6 X%GD0h]X# http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m
n1*&%d'7 Re*| $r# 直到发现这个例子后才清楚各个参数所代表的具体意义。
I( ]BMMj -=$% { 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?
20UqJM8 Ot #M5_e m4kN p = hygepdf(0:5,100,20,10)
$s- 9|Lbs` <t{?7_ 8 p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
2yln 7[a |e *Gz D 详细可参见：
M%$ D T http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 *O@sh A3AP51
! 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@8S5K J FUaI2 x = 0:5
#>8T*B p = hygepdf(x,100,20,10);
{~"7vkc+ plot(x,p,':k*')
