clear
format compact
nntwarn off

S1 = 12;

P=-1:.1:-.5;
T=[-.9602 -.5770 -.0729 .3771 .6405 .6600];

[R,Q]=size(P);
[S2,Q]=size(T);
[W1,B1]=nwtan(S1,R);
[W2,B2]=rands(S2,S1);

disp_freq = 500;
max_epoch = 15000;
err_goal = 0.1;
lr = 0.01;
error = zeros(1,max_epoch);


A1=tansig(W1*P,B1);
A2=purelin(W2*A1,B2);
E=T-A2;
SSE=sumsqr(E);



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

    D2=deltalin(A2,E);
    D1=deltatan(A1,D2,W2);
    [dW2,dB2] = learnbp(A1,D2,lr);
    [dW1,dB1] = learnbp(P,D1,lr);
    W1=W1 + dW1;
    B1 = B1 + dB1;
    W2=W2 + dW2;
    B2 = B2 + dB2;
    A1=tansig(W1*P,B1);
	A2=purelin(W2*A1,B2);
	E=T-A2;
    SSE=sumsqr(E);
    error = [error SSE];

    if(rem(epoch,disp_freq) == 0)
        epoch
        SSE
        plot(P,T,'r',P,A2,'g')
        pause(exp(-10))
    end

end
epoch
SSE