samer@32: function S=magspec(X,N)
samer@32: % magspec - get magnitude spectra of columns of x (v. 2)
samer@32: %
samer@32: % magspec :: [[N,L]] -> [[M,L]] :- M=dftbins(N).
samer@32: %
samer@32: % Version 2 corrects error in V. 1 - the wrong bands were being
samer@32: % doubled up in the power reckoning. This version now guarantees
samer@32: % that sum(magspec(x).^2) = sum(x.^2).
samer@32: 
samer@32: if nargin<2, N=size(X,1); end
samer@32: 
samer@32: bins=1+floor(N/2);
samer@32: Y=fft(X,N);
samer@32: S=abs(Y(1:bins,:))*sqrt(2/N); % sqrt of double of total power per band
samer@32: singles=1:ceil(N/2):bins;
samer@32: S(singles,:)=S(singles,:)/sqrt(2); % undo double counting of singletons
samer@32: