%Examples for the ELEC241 Matlab tutorial
%Chris Rozell - 8/26/03 (crozell@rice.edu)

t   = [0:.01:1];                % independent (time) variable
A = 8;                          % amplitude

f_1 = 2;                        % create a 2 Hz sine wave lasting 1 sec
s_1 = A*sin(2*pi*f_1*t);

f_2 = 4;                        % create a 4 Hz sine wave lasting 1 sec
s_2 = A*sin(2*pi*f_2*t);


%plot the 2 Hz sine wave in the top panel
figure
subplot(3,1,1)
plot(t, s_1)
title('2 Hz sine wave')
ylabel('Amplitude')

%plot the 4 Hz sine wave in the middle panel
subplot(3,1,2)
plot(t, s_2)
title('4 Hz sine wave')
ylabel('Amplitude')

%plot the summed sine waves in the bottom panel
subplot(3,1,3)
plot(t, s_1+s_2)
title('Summed sine waves')
ylabel('Amplitude')
xlabel('Time (s)')

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% create the same sine waves using Euler's relations
s_3 = (exp(j*2*pi*f_1*t) - exp(-j*2*pi*f_1*t))/(2*j);
s_4 = imag(exp(j*2*pi*f_2*t));

% plot the 2 and 4 Hz waves together in the same panel
figure
subplot(2,1,1)
plot(t,s_3, 'b-')
hold on
plot(t, s_4, 'r--')
ylabel('Amplitude')

% again plot the sum in the bottom panel
subplot(2,1,2)
plot(t, s_3+s_4)
ylabel('Amplitude')
xlabel('Time (s)')