w = [0:1:500]*pi/500;                           % freqency between 0 and +pi, [0,pi] axis divided into 501 points.

H = exp(j*w) ./ (exp(j*w) - 0.9 * ones(1,501));

magH  = abs(H);  angH  = angle(H);  realH  = real(H);  imagH  = imag(H);

%% --------------------------------------------------------------------

%%              START H's  mag ang real imag

%% --------------------------------------------------------------------

figure('NumberTitle', 'off', 'Name', 'H its Magnitude and Angle, Real and Imaginary Part');

set(gcf,'Color','white');

subplot(2,2,1); plot(w/pi,magH); grid on;  axis([0,1,0,10]);

title('Magnitude Part');

xlabel('frequency in \pi units'); ylabel('Magnitude  |H|');

subplot(2,2,3); plot(w/pi, angH/pi); grid on; % axis([-1,1,-1,1]);

title('Angle Part');

xlabel('frequency in \pi units'); ylabel('Radians/\pi');

subplot('2,2,2'); plot(w/pi, realH); grid on;

title('Real Part');

xlabel('frequency in \pi units'); ylabel('Real');

subplot('2,2,4'); plot(w/pi, imagH); grid on;

title('Imaginary Part');

xlabel('frequency in \pi units'); ylabel('Imaginary');

%% -------------------------------------------------------------------

%%             END X's  mag ang real imag

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