function out=mybp() 
clear all
N=16;         %學(xué)習(xí)樣本個數(shù)(number)
In=4;        %輸入層神經(jīng)元個數(shù)（Input number)
Hn=10;        %隱層神經(jīng)元個數(shù)(Hidden number)
On=4;        %輸出層神經(jīng)元個數(shù)(Output number)
times=800;                %學(xué)習(xí)次數(shù)
eta_hi=0.9;                 %定義隱層到輸入層的學(xué)習(xí)速率
eta_oh=0.9;                 %定義輸出層到隱層的學(xué)習(xí)速率
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

% 主程序部分
fid = fopen('trainingdata.txt');                
X= (fscanf(fid,'%g',[In N]))'           %讀入待訓(xùn)練數(shù)據(jù)
fid = fopen('teacherdata.txt');                
T= (fscanf(fid,'%g',[On N]))'           %讀入期望輸出
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
Whi=initw(In,Hn);       %輸入層和隱層之間權(quán)值的初始化
Woh=initw(Hn,On);       %隱層和輸出層之間權(quán)值的初始化
thh=initw(1,Hn);        %隱層閾值初始化(threshold of hidden)
tho=initw(1,On);        %輸出層閾值初始化(threshold of output)
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%計(jì)算第n次迭代時的實(shí)際輸出%%%%%%%%%%%%%%%% 
for m=1:times       
    E=0;  
    for n=1:N   
        temp1=X(n,:);                %取出X第n行，即第n組學(xué)習(xí)樣本
        Teacher=T(n,:);                %讀入教師數(shù)據(jù)給Teacher
        for j=1:Hn                    
            temp2=Whi(:,j);        %取出Whi第j列，即第j個神經(jīng)元所對應(yīng)的權(quán)值
            net_h(j)=temp1*temp2+thh(j);                       
            Y(j)=f1(net_h(j));      %求出隱層的輸出
        end         
        for k=1:On
            temp3=Woh(:,k);         %取出Woh第k列，即第k個神經(jīng)元所對應(yīng)的權(quán)值
            net_o(k)=Y*temp3+tho(k);            
            Z(k)=f2(net_o(k));       %求出輸出層的輸出    
        end
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
        for j=1:Hn 
            for k=1:On                  %輸出層到隱層的權(quán)值調(diào)整
            delta_o(k)=(Teacher(k)-Z(k))*derif2(net_o(k));
            delta_Woh(j,k)=eta_oh*delta_o(k)*Y(j);
            end
        end       
        for k=1:On, 
            delta_tho(k)=eta_oh*delta_o(k);  %輸出層閾值的變化
        end        
        for i=1:In                      %隱層到輸入層的權(quán)值調(diào)整
            for j=1:Hn 
                sigma=0;
                for k=1:On                                      
                sigma=sigma+Woh(j,k)*delta_o(k);                            
                end
                delta_h(j)=derif1(net_h(j))*sigma;  
                delta_Whi(i,j)=eta_hi*delta_h(j)*temp1(i);
            end
        end  
        for j=1:Hn     
            delta_thh(j)=eta_hi*delta_h(j);  %隱層閾值的變化
        end
        Woh=Woh+delta_Woh;          %更新輸出層到隱層的權(quán)值
        Whi=Whi+delta_Whi;          %更新隱層到輸出層的權(quán)值
        tho=tho+delta_tho;          %更新輸出層閾值
        thh=thh+delta_thh;          %更新隱層閾值
        E=E+Err(Teacher,Z,On);      %計(jì)算誤差
        [temp1 Teacher Z Err(Teacher,Z,On)]
    end
    Error(m)=E;
end
out=plot(Error);
save W Woh Whi tho thh



%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%Programmed by XFX, Thanks for advice: fangxur@gmail.com