[color=red][/color][quote author=Fu-Kwun Hwang link=topic=752.msg2843#msg2843 date=1222677673]
The following applet shows the superposotion of two waves.
Blue curve represent wave move in x direction: y(t)=A*sin(k*x-w*t);
where k=wavelength/(2*pi),  w=period/(2*pi)

Green curve represent wave move in +x or -x direction: y(t)=A*sin(k*x-w*t+phi) or y(t)=A2*sin(k*x+w*t+phi) :Click checkbox[b]same V[/b] to select the first one.

Cyan curve is the sum of the above two waves.