LibSVM采用高斯核时，网格法调整两个参数的代码

% 目录：E:\other\matlab 2007a\work\DCT\DCT_original\network.m and DCTForClassification.m

%此处代码相当于网格法来搜索这两个参数，Cvalue取10个值分别是100，200到1000.Gamma取60个值，分别是0.00002

%到0.00009；0.0002到0.0009；0.002到0.009；依次类推
% This code has been checked by Libing Wang. It should not have any problem.

Cvalue = 0;

Fold = 4; % 4 fold cross validation

C=0;

G=0;

Loocv=10;

for i = 1:10

    Cvalue=Cvalue+100;

    Gamma=0.00001;

    

    for j =1:60

        if Gamma>=1

            Gamma=Gamma+1;

        elseif Gamma>=0.1 

            Gamma=Gamma+0.1;

        elseif Gamma>=0.01

            Gamma=Gamma+0.01;

        elseif Gamma>=0.001 

            Gamma=Gamma+0.001;

        elseif Gamma>=0.0001

            Gamma=Gamma+0.0001;     

        elseif Gamma>=0.00001;

            Gamma=Gamma+0.00001;

        end

              

        SVMParameter=sprintf('-c %f -g %f -v %d',Cvalue,Gamma,Fold);

        LoocvTemp = svmtrain(gnd_Train, fea_Train, SVMParameter);        

        if LoocvTemp > Loocv

           Loocv=LoocvTemp;

           C=Cvalue;

           G=Gamma;

        end

    end

end

SVMParameter = sprintf('-c %f -g %f',C,G);

model = svmtrain(gnd_Train, fea_Train,SVMParameter);

[predict_label, rate, dec_values] = svmpredict(gnd_Test, fea_Test, model); 

accuracy = rate(1) %recognition rate