function?data=dbmoon（Ndrw）
%?Usage:?data=dbmoon（Ndrw）
%?doublemoon.m?-?genereate?the?double?moon?data?set?in?Haykin‘s?book?titled
%?“neural?networks?and?learning?machine“?third?edition?2009?Pearson
%?Figure?1.8?pp.?61
%?The?data?set?contains?two?regions?A?and?B?representing?2?classes
%?each?region?is?a?half?ring?with?radius?r?=?10?width?=?6?one?is?upper
%?half?and?the?other?is?lower?half
%?d:?distance?between?the?two?regions
%?will?generate?region?A?centered?at?（0?0）?and?region?B?is?a?mirror?image
%?of?region?A?（w.r.t.?x?axis）?with?a?（r?d）?shift?of?origin
%?N:?#?of?samples?each?class?default?=?1000
%?d:?seperation?of?two?class?negative?value?means?overlapping?（default=1）
%?r:?radius?（default=10）?w:?width?of?ring?（default=6）
%?
%?（C）?2010?by?Yu?Hen?Hu
%?Created:?Sept.?3?2010

%?clear?all;?close?all;
if?nargin<4?w=6;
elseif?nargin<3?r=10;
elseif?nargin<2?d=1;
elseif?nargin?end

%?generate?region?A:
%?f