function [omega,X]=fouriertransform(x,step);
%This function computes an approximation of the Fourier transform.
%Let N=length(x). It assumes signal x are the values of the signal
%corresponding to the time vector
%t=(-N/2:N/2-1)*step;
%
%Output: a frequency vector omega (in radians) and the corresponding Fourier
%transform
N=length(x);

X=fftshift(fft(x))*step;
omega=2*pi*(-N/2:N/2-1)/N/step;