The 27 - periodic function f(r) = -1 from -T to 0 and f(r) = 1 from 0 to r has Fourier series sin(3r) sin(5r) +.. 4 sin(z) + terms of the Fourier series of f(x) on the same coordinate axes. The Gibbs phenomenon is the oscillation that overshoots the jump discontinuity - it never dies down with more terms. Use a CAS to graph f(x) (with f(0) = 0) and the first 10 %3D 3