Eigenvalues: k1=4, k2=1
Phase shifts: s1=s2=1, c1=2, c2=1

u=u1+u2 (decay decomposition)

Below is a combined plot of the first decay function -u1(x,t) (in red)
and the second decay function -u2(x,t) (in blue) versus x.  Notice the
exchange of identities.

time steps: t=-14, -12, -10,...,12.