% MATLAB script for Illustrative Problem 4, Chapter 6.echo onLength=101;Fs=10000;W=2000;Ts=1/Fs;n=-(Length-1)/2:(Length-1)/2;t=Ts*n;h=2*W*sinc(2*W*t);        % The rectangular windowed version follows...N=61;rec_windowed_h=h((Length-N)/2+1:(Length+N)/2);% Frequency response of rec_windowed_h follows[rec_windowed_H,W1]=freqz(rec_windowed_h,1);% to normalize the magnituderec_windowed_H_in_dB=20*log10(abs(rec_windowed_H)/abs(rec_windowed_H(1)));% The Hanning windowed version follows...hanning_window=hanning(N);hanning_windowed_h=h((Length-N)/2+1:(Length+N)/2).*hanning_window.';[hanning_windowed_H,W2]=freqz(hanning_windowed_h,1);hanning_windowed_H_in_dB=20*log10(abs(hanning_windowed_H)/abs(hanning_windowed_H(1)));% the plotting commands follow