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
kR7IZo" q >wej1#\3 ans =
PDREwBX TGdD7n&Ehh NaN
Ooc,R( i
cQsA 查看了一下帮助 help hygepdf
Tcz67&c |W ppN96-]^0 HYGEPDF Hypergeometric probability density function.
1m|Oi%i4 T mH# Y = HYGEPDF(X,M,K,N) returns the hypergeometric probability
#~I%qa"_pa density function at X with integer parameters M, K, and N.
$.R$I&U Note: The density function is zero unless X is an integer.
j +@1frp m0paGG The size of Y is the common size of the input arguments. A scalar input
3*CF !Y% functions as a constant matrix of the same size as the other inputs.
@{@x2'-A 8'Xpx+v See also hygecdf, hygeinv, hygernd, hygestat, pdf.
93kSB F# D}HW7Hnu^ Reference page in Help browser
%N|7<n<S doc hygepdf
{[hV ['Awv -x_b^)x~b7 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：
# lM!s L'J$jB5cP http://ccpublic-1.central.cranfield.ac.uk/2001DMSOMFRC/pr062320/Matlab/stats/hygepdf.m t# &^ -; %.pX!jL 直到发现这个例子后才清楚各个参数所代表的具体意义。
9j49#wG0"B wHWd~K_q Suppose you have a lot of 100 floppy disks and you know that 20 of them are defective. What is the probability of drawing 0 through 5 defective floppy disks if you select 10 at random?
2fO ~%!.G L= Dd` p = hygepdf(0:5,100,20,10)
Q pz01x '-D-H}%;}M p = 0.0951 0.2679 0.3182 0.2092 0.0841 0.0215
=9i:R !,W ` R!0uRu 详细可参见：
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v o US http://www.physnet.uni-hamburg.de/physnet/matlab/help/toolbox/stats/hygepdf.html#4257 ]r$S{< _{_LTy%[ 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
Up`$U~%- ~ I ]kY% x = 0:5
YMIDV- p = hygepdf(x,100,20,10);
Fq&@dxN3 plot(x,p,':k*')
