function u=mseries(L)
y1=1;y2=1;y3=1;y4=0;
for i=1:1:L
    x1=xor(y3,y4);
    x2=y1;
    x3=y2;
    x4=y3;
    y(i)=y4;
    if y(i)>0.5
        u(i)=-0.03;
    else u(i)=0.03;
    end
    y1=x1;
    y2=x2;
    y3=x3;
    y4=x4;
end