% plot_echo(w, x, r)
%
% Generates plots for evaluating an echo canceler simulation.
%    
% Input arguments:
%    w  : The adaptive filter coefficient vector
%    x  : The microphone signal
%    r  : The residual signal
%    x and r can be either vectors or wave files
%       Author : John Garas PhD.%       Version 2.1, Release October 2002.%       Copyright (c) DSP ALGORITHMS 2000-2002.