Hi! 1. The problem statement, all variables and given/known data I have this x'[t] + x[t] = a + Sin[b*t] diff.equ that I would like to solve with matlab/simulink. Let set a=1, b=1 and x(0)=2 2. Relevant equations I know that x(t) = 1/2 e^-t (-cos(t) e^t+sin(t) e^t+2 e^t+3) and what it look like (see pic). I aslo got the transfer equ G(s) from Laplace and it should be: G(s) = (a/s+b/(b^2+s^2))/(s+1), 3. The attempt at a solution The only thing I dont get right is the initial value as you can see at the pic. It also shows what it should look like. What do I do wrong? It should be easier to use the transfer equ G(s), but I dont get that right either. Any suggestions? http://img205.imageshack.us/img205/821/reglerth3.jpg [Broken] Thank you!