The blue curve you see above represents the graph of a function θ(x,t) for a fixed value of t.
The coordinate x varies in the horizontal direction. The left side of the white frame corresponds to x=-0.5, and the right side to x=0.5. The top of the white frame is θ=1, and the bottom θ=-1. The function θ is extended outside of the box as zero.
When you click "Start", the graph will start evolving following the equation.
A more feature rich page is avaliable here.
Luis Silvestre. Last update: August 7th, 2013.