Here's a small toy to play with the heat equation: https://math.berkeley.edu/~kmill/toys/heat/heat.html https://math.berkeley.edu/~kmill/toys/heat/heat.html (it

Here's a small toy to play with the heat equation: https://math.berkeley.edu/~kmill/toys/heat/heat.html https://math.berkeley.edu/~kmill/toys/heat/heat.html (it probably doesn't work on mobile---sorry!) It shows the Fourier transform of the curve you draw, and how each summand decays through time. There's also a wave equation toy: https://math.berkeley.edu/~kmill/toys/wave/wave.html https://math.berkeley.edu/~kmill/toys/wave/wave.html