Centered three-level wave scheme
= Centered three-level wave scheme
For
$$
v_m^{n+1}-2\rho v_m^n+v_m^{n-1}
=\mu(v_{m+1}^n-2v_m^n+v_{m-1}^n),
$$
the amplification polynomial is
$$
G^2+(4\mu\sin^2(\theta/2)-2\rho)G+1=0.
$$
All modes have unit-modulus roots only when $\rho=1$ and $0\leq\mu\leq1$.