Chladni figures are wavy lines produced by scattered salt or sand on an elastic material of a given shape, possibly constrained at the edges or at a point in the center, and forced to vibrate with a violin bow. The modes of vibration can be identified because these small particles end up in the places of zero vibration, which happens at those parts of the surface that are stationary, namely at the nodes of vibration, where n harmonics cancel.

For the 2D solution, the condition cos(nπx/L) cos(mπy/L)-cos(mπx/L) cos(nπy/L)=0 holds, for integer values m and n. The solution is uninteresting for n=m, and for gcd(n₁,m₂)=gcd(n₂,m₁), the plots are the same.