Question

Solve the wave equation for u(x, y, t) in the rectangle 0 < x < L, 0 < y < H with
initial conditions u(x, y, 0) = φ(x, y), ∂u/∂t(x, y, 0) = ψ(x, y) and with ∂u/∂n = 0 on the
boundary (i.e. the normal derivative vanishes)