function fv=idft(N,fc)

i=sqrt(-1);
h=2*pi/N; wn=exp(-i*h);
for k=0:N-1,
  s= 0;
  for j=0:N-1
%    s = s + fc(j+1)*wn^((k-N/2)*j);
     s = s + fc(j+1)*exp( -(2*pi*i*j*k)/N );
  end
 
  fv(k+1)=s/N;
end