filter_design2(Fc,Fs,N);

function [B,A] = filter_design2(Fc,Fs,N);

% Usage of the filter: Y = FILTER(B,A,X). 
%
% Requires the Signal Processing Toolbox. 
% Design Butterworth 2Nth-order one-third-octave filter. 

f1 = 2^(-1/6)*Fc; 
f2 = 2^(1/6)*Fc; 
f1 = f1/(Fs/2);
f2 = f2/(Fs/2);
[B,A] = butter(N,[f1,f2]);