z$ on $C$ by means of a complex-valued function of a real variable $t$
                    called a <em>parametrization</em> of $C$:
                    \begin{equation}\label{parcurve}
                    z(t) = x(t) + i y(t), \quad a\leq t\leq b.
                    \end{equation}
                </p>

                <p>
                    The point $z(a) = x(a) + i y(a)$ or $z_0 = (x(a), y(a))$ is called the <em>initial point</em> of
                    $C$ and $z(b) = x(b) + iy(b)$
                   