1. The problem statement, all variables and given/known data I am given an initial- and boundary value problem for the two dimensional wave function, and I must solve it by d'Alembert's method. It is all good, but I am given the initial velocity: [itex]g(x)=x(\pi-x)[/itex]. I have to find the odd extension of this on the interval [itex]-\pi[/itex] to [itex]\pi[/itex]. I don't like using Fourier series, because I must integrate the odd extension. Is there any way to do this? Thanks in advance, sincerely, Niles.