Xo = 0;%lower limit
h = .05;%intervals
Xn = 6;%upper limit
lam = -1;
y = sin(Xo);%the function at Xo
dy = lam.*y + cos(Xo) - lam.*sin(Xo);%the derivative of y at Xo
for x = Xo:h:Xn
    Y = y + h.*dy;%the value of the tangent line at x
    if (rem(x,2)==0)
        %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
        func = sin(x);%actual function
        %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
        Error = func - Y;
        Rel = Error/func;
        AError = (h./2).*((cos(x)+lam.*sin(x)-exp(lam.*x))./(1+lam.^2));
        [x, Y, Error, Rel, AError]
    end    
    y = Y;%function at Xn
    %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    dy = lam.*y + cos(x) - lam.*sin(x);%derivative of y at Xn
    %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%    
end