samer@32: % tri_filterbank - Bank of triangular filters 
samer@32: %
samer@32: % tri_filterbank ::
samer@32: %    E:[[M+2]->nonneg] ~'array of filter edge frequencies',
samer@32: %    F:[[N]]           ~'array of bin frequencies for input spectra'
samer@32: % -> [[M,N]]           ~'matrix to multiply by input spectra'.
samer@32: %
samer@32: % Modelled on Malcom Slaney's code in Auditory toolbox.
samer@32: 
samer@32: function W=tri_filterbank(edges,f)
samer@32: 	M = length(edges)-2; % total number of filters to prepare
samer@32: 
samer@32: 	lower  = edges(1:M);
samer@32: 	center = edges(2:M+1);
samer@32: 	upper  = edges(3:M+2);
samer@32: 
samer@32: 	W = zeros(M,length(f));
samer@32: 	for i=1:M
samer@32: 		W(i,:) = (f>lower(i) & f<=center(i)).*(f-lower(i))/(center(i)-lower(i)) ...
samer@32: 			 	 + (f>center(i) & f<upper(i)).*(upper(i)-f)/(upper(i)-center(i));
samer@32: 	end
samer@32: 	W=sparse(W);
samer@32: end