function [K] = IBR (J,NU)
% This function is used by Fast Fourier Transform (Algorithm 8.3)
% to perform bit reversal.
 J1 = J;
 K = 0;
 for JJ = 1 : NU 
 J2 = floor(J1/2);
 K = 2*K+J1-2*J2;
 J1 = J2;
 end;