function?[bestaccbestcbestg]?=?SVMcgForClass（train_labeltraincmincmaxgmingmaxvcstepgstepaccstep）
%SVMcg?cross?validation?by?faruto

%%
%?by?faruto
%Email:patrick.lee@foxmail.com?QQ:516667408?http://blog.sina.com.cn/faruto?BNU
%last?modified?2010.01.17

%%?若轉載請注明：
%?faruto?and?liyang??LIBSVM-farutoUltimateVersion?
%?a?toolbox?with?implements?for?support?vector?machines?based?on?libsvm?2009.?
%?
%?Chih-Chung?Chang?and?Chih-Jen?Lin?LIBSVM?:?a?library?for
%?support?vector?machines?2001.?Software?available?at
%?http://www.csie.ntu.edu.tw/~cjlin/libsvm

%%?about?the?parameters?of?SVMcg?
if?nargin?????accstep?=?4.5;
end
if?nargin?????cstep?=?0.8;
????gstep?=?0.8;
end
if?nargin?????v?=?5;
end
if?nargin?????gmax?=?8;
????gmin?=?-8;
end
if?nargin?????cmax?=?8;
????cmin?=?-8;
end
%%?X:c?Y:g?cg:CVaccuracy
[XY]?=?meshgrid（cmin:cstep:cmaxgmin:gstep:gmax）;
[mn]?=?size（X）;
cg?=?zeros（mn）;

eps?=?10^（-4）;

%%?record?acc?with?different?c?&?gand?find?the?bestacc?with?the?smallest?c
bestc?=?1;
bestg?=?0.1;
bestacc?=?0;
basenum?=?2;
for?i?=?1:m
????for?j?=?1:n
????????cmd?=?[‘-v?‘num2str（v）‘?-c?‘num2str（?basenum^X（ij）?）‘?-g?‘num2str（?basenum^Y（ij）?）];
????????cg（ij）?=?libsvmtrain（train_labe