harmonic oscillator with friction.
        The equations of motion are given by <span class="emphasis"><em>x'' = -x + &#947; x'</em></span>.
        Odeint only deals with first order ODEs that have no higher derivatives than
        x' involved. However, any higher order ODE can be transformed to a system
        of first order ODEs by introducing the new variables <span class="emphasis"><em>q=x</em></span>
        and <span class="emphasis"><em>p=x'</em></span> such that <span class="emphasis"><em>w=(q,p)