Writing a Fourier series as f(θ) = 1/2 a_0 + sum_(n = 1)^(m - 1) sinc((n π)/(2m))[a_n cos(n θ) + b_n sin(n θ)], where m is the last term, reduces the Gibbs phenomenon. The sinc(x) terms are the known as the Lanczos σ factors. Note that incorrectly lists the upper index of the sum as m, while Hamming gives the correct form reproduced above.

Fourier series | Gibbs phenomenon | sinc function