Documentation

Calculate a fast Fourier transform of a complex series. The transformed data overwrite the untransformed data. The output series store in the usual order, e.g. 0, dF, ..., F_Ny-dF, -F_Ny, ..., -dF.

Parameters:

x - Complex series to be transformed.
N - Number of elements in the series. N may be any number > 1.
Dir - Select between transform (1) and inverse transform (0).