samer@32: % formants - Compute formants from LPC coefficients
samer@32: function F=formants(a,M,fs)
samer@32: 
samer@32: const=fs/(2*pi);
samer@32: if all(isfinite(a))
samer@32: 	rts=roots(a);
samer@32: 
samer@32: 	fx = const*angle(rts);
samer@32: 	bw = -2*const*log(abs(rts));
samer@32: 
samer@32: 	F = log(sort(fx(fx>90 & fx<4000 & bw<700)));
samer@32: 	N = length(F);
samer@32: 	if N<M, F=[F;nan(M-N,1)];
samer@32: 	else F=F(1:M); end
samer@32: else
samer@32: 	F=nan(M,1);
samer@32: end
samer@32: % only first 3?