% f = iFour(F,xi,x) computes the inverse Fourier transform 
% using the definition
%      f(x) = int(F(xi)*exp(2*pi*i*xi*x),xi,-inf,inf)
% 
% x and xi must be declared as symbolic variables, e.g., using
%      syms x xi
function f = iFour(F,xi,x)
f = 2*pi*subs(ifourier(F,xi,x),x,2*pi*x);
