, a trigonometric series
is any series
of the form:
It is called a Fourier series when the terms and have the form:
where is an integrable function.
It is not that case that every trigonometric series is a Fourier Series. A particular question of interest is given a trigonometric series, for which values of x does the series converge.
- "Trigonmetric Series" by A. Zygmund