Harmonic function, mathematical function of two variables having the property that its value at any point is equal to the average of its values along any circle around that point, provided the function is defined within the circle. An infinite number of points are involved in this average, so that it must be found by means of an integral, which represents an infinite sum.

The harmonic wave equation is given by y(x,t)=Rsin{2 π / λ(vx-t)+ Ï•} where R is amplitude λ λis wavelength v is velo of wave Ï• is initial phase.