function rhs = wave1_f(x,u)
% odefile for wave equation code (to be called by ode45)
% 
% 2004-03-01 kfp

w = 1.0;
a = 100.0;
rhs = [u(2);-2*a*(sech(a*x))^2*u(2)/(3+tanh(a*x))-4*w^2*u(1)/(3+tanh(a*x))^2];
