function snr = calculateSNR(hwfft,f,nsig)% snr = calculateSNR(hwfft,f,nsig=1) Estimate the signal-to-noise ratio, % given the in-band bins of a (Hann-windowed) fft and % the location of the input signal (f>0).% For nsig=1, the input tone is contained in hwfft(f:f+2); %  this range is appropriate for a Hann-windowed fft.% Each increment in nsig adds a bin to either side.% The SNR is expressed in dB.if nargin<3    nsig = 1;endsignalBins = [f-nsig+1:f+nsig+1];signalBins = signalBins(signalBins>0);signalBins = signalBins(signalBins<=length(hwfft));s = norm(hwfft(signalBins));		% *4/(N*sqrt(3)) for true rms value;noiseBins = 1:length(hwfft);noiseBins(signalBins) = [];n = norm(hwfft(noiseBins));if n==0    snr = Inf;else    snr = dbv(s/n);end