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
/hQTV!\u 7: )= ans =
6`J*{%mP >h( n8wTP NaN
hV)D,oN3 Uz} #. 查看了一下帮助 help hygepdf
b>er 'U .-awl1 W HYGEPDF Hypergeometric probability density function.
(1^AzE%U+Z RpOGY{[)[ Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
gp`$/ ci density function at X with integer parameters M, K, and N.
h.l^f>, / Note: The density function is zero unless X is an integer.
6k|o<`~, /q^)thJ~ The size of Y is the common size of the input arguments. A scalar input
g=XvqD< functions as a constant matrix of the same size as the other inputs.
LPc)-t|p" wqk D See also hygecdf, hygeinv, hygernd, hygestat, pdf.
{^a"T'+ | (JxtQqQg Reference page in Help browser
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rTzMO doc hygepdf
iVTC"v Nj rF":'Y 超几何分布参数较多，这里关于三个参数的指代不详。又在互联网上查了相关资料，包括该函数的定义式：
l=GcgxD+"d u!hY
bCB http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m p.A_,iE Vzn0 ; 直到发现这个例子后才清楚各个参数所代表的具体意义。
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nR ($pN OG H 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?
yw Tt<;
7 X E&[o p = hygepdf(0:5,100,20,10)
SR!EQ< z$4g9 p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
/99S<U2ej BZ* ',\o 详细可参见：
!}[}YY?',i http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 = . a} n("Xa#mY[ 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
Le RyS] I! eu|_cF x = 0:5
c!*yxzs\ p = hygepdf(x,100,20,10);
KSDz3q e plot(x,p,':k*')
