The order n Fourier exponential series expansion of expr is by default defined to be .
The coefficient ck is defined to be and the coefficient dk is defined to be .
Different choices for the period of expr can be specified using the option FourierParameters.
With the setting FourierParameters->{a, b}, expr is assumed to have a period of , and the order n Fourier exponential series expansion computed by FourierTrigSeries is . Here, the coefficient ck is defined to be and the coefficient dk is defined to be .