I’ve decided to build a pendulum wave and write an Instructable to document the process.
In the meantime, here’s a matlab demonstration showing how I hope it will behave. Matlab function is posted after the video.
%Created by Eric Cox - https://ericboy.wordpress.com - 5/17/2012
function  = PWT(n,f,df,t)
%This function plots pendulum wave motion as seen from the top view.
% n is the number of pendulums, f is the frequency of the first pendulum
% in the wave, df is the incremental change in frequency between pendulums
% (added), t is the time to display the animation
%set initial time to zero.
%preallocate lengths of matrices.
%for each value in x,y matrices, populate with value at current t.
%Plot pendulum wave
axis([0 n+1 -1.5 1.5]);
%Increment loop time