A sawtooth, a square and a triangle wave, each summed from its first ten nonzero Fourier terms, f(t) = ∑ bₙ sin(nt). Each term is a circle of radius |bₙ| turning n times per period. The sawtooth has bₙ = 2(−1)ⁿ⁺¹/(nπ), the square 4/(nπ) for odd n, the triangle ±8/(n²π²)