samer@32: function F=dftfmap(N,Fs)
samer@32: % dftfmap - Frequency map for DFT of real signal 
samer@32: %
samer@32: % dftfmap :: N:natural, real ~'sampling rate' -> dmap(dftbins(N)).
samer@32: 
samer@32: 	M=dftbins(N);
samer@32: 	F=dmap(M,@map,@revmap);
samer@32: 
samer@32: 	function I=map(X)
samer@32: 		I=round(N*X/Fs);
samer@32: 		I(X<0)=-inf;
samer@32: 		I(X>Fs/2)=inf;
samer@32: 	end
samer@32: 
samer@32: 	function X=revmap(I)
samer@32: 		I=shiftdim(shiftdim(I),-1);
samer@32: 		X1=Fs*(2*I-3)/(2*N);
samer@32: 		X2=Fs*(2*I-1)/(2*N);
samer@32: 		X1(I<=1)=0;
samer@32: 		X2(I>=M)=Fs/2;
samer@32: 		X=cat(1,X1,X2);
samer@32: 	end
samer@32: end
samer@32: