Problem: Let $\mu$ be a unitary operator on a finite dimensional complex inner product space. Show that there exists a self-adjoint linear operator $\rho$ such that $$\mu=e^{i\rho}$$.
I found this result in Steve Roman's Advanced Linear Algebra book. I am able to see that the R.H.S.of the above equation is unitary but I am unable to construct a $\rho$ given a $\mu$.
Please help.