NFourierSeries[expr, t, n] gives a numerical approximation to the order n Fourier exponential series expansion of expr, where expr is a periodic function of t with period 1.
The numerical approximation to the order n Fourier exponential series expansion of expr is by default defined to be Fk2kt, where Fk is given by .
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 NFourierSeries is Fk2bkt, where Fk is given by .
In addition to the option FourierParameters, NFourierSeries can also accept the options available to NIntegrate. These options are passed directly to NIntegrate.