clear all
nntwarn off
format compact


P=-1:.1:-.5;

T=[-.9602 -.5770 -.0729 .3771 .6405 .6600];

[R,Q]=size(P);
[S3,Q]=size(T);

S1=13;
S2=7;

[W1, B1]=nwtan(S1,R);
[W2, B2]=nwtan(S2,S1);
[W3, B3]=rands(S3,S2);


disp_freq=100;
max_epoch=20000;
err_goal=1e-30;
lr=0.01;
error=[];



for epoch=1:max_epoch,

    A1=tansig(W1*P,B1);
    A2=tansig(W2*A1,B2);
    A3=purelin(W3*A2,B3);
    E = T - A3;

    D3=deltalin(A3,E);
    D2=deltatan(A2,D3,W3);
    D1=deltatan(A1,D2,W2);

    [dW1, dB1]=learnbp(P,D1,lr);
    W1=W1+dW1;
    B1=B1+dB1;

    [dW2, dB2]=learnbp(A1,D2,lr);
    W2=W2+dW2;
    B2=B2+dB2;

    [dW3, dB3]=learnbp(A2,D3,lr);
    W3=W3+dW3;
    B3=B3+dB3;


    SSE=sumsqr(E);
    error=[error SSE];

    if SSE<err_goal,
        epoch=epoch-1;
        break
    end

    if(rem(epoch,disp_freq)==0)
        fprintf('%d/%d,  SSE = %g\n', epoch, max_epoch, SSE);
        plot(P,A3,'r',P,T,'g')
        pause(1e-500)
    end
end