clc; close all; clear all;
t=0:0.1:100; 
x=0:0.3:30; 
k=1.3; w=0.9; n=length(t);
y=cos(k*x-w*t(1))+cos(x-t(1));
h=plot(x,y); 
set(h,'color','g');
axis([0 30 -3 3]);
set(h,'EraseMode','xor');
 pause; 
for i=2:n;
y=cos(k*x-w*t(i))+cos(x-t(i));
 set(h,'XData',x,'YData',y);
 pause(0.1)
end;