- an infinite series that involves linear combinations of sines and cosines and approximates a given function on a specified domain.
- an infinite trigonometric series of the form 1/2 a 0 + a 1 cos x + b 1 sin x + a 2 cos 2 x + b 2 sin 2 x + …, where a 0, a 1, b 1, a 2, b 2 … are the Fourier coefficients . It is used, esp in mathematics and physics, to represent or approximate any periodic function by assigning suitable values to the coefficients
