function rs = realifft(data, N)% inverse fft for fourier coefficents from real valued  original data% needs the length of the original time series from which the fft was computed% see also : realfftdata = data(:);if mod(N,2) 	% odd length	data = [data ; conj(data(end:-1:2))];  else			% even length	data = [data ; conj(data(end-1:-1:2))];  end rs = real(ifft(data)); % remove small imaginary components introduced by rounding errors