Solves the difficulty of computing and visualizing the DFT of an array that can be caused by (a) the units of frequency, (b) the mirroring effect, (c) the complex nature.
% Inputs: -t, a time array evenly spaced 0:tstep:T
% -x, the function array
% -pl, {0,1} to display plot

% Outputs: - f a frequency array
% - G, the fourier transform, starting on the coefficiente % G1 and not in G0! (the value of wave number 0
% component is taken out, later it is explained why)