Question

Using Matlab:

If x(n)=cos(5π n/6) and y(n)=cos(4π n/9), stem plot the sum z(n)=x(n)+y(n) over n=0:100. Write the arguments of the sinusoids as (2π n M/N). By finding the least common multiple of the denominators, determine the period of z(n). Put the period of the sum z(n) in the title of the plot. Stem plot the samples of the first period in blue, the second in red and the remainder in green in your plot.

Answer 1

n=0:100;
x=cos(5*pi*n/6);
y=cos(4*pi*n/9);
z=x+y;
hold on
stem(0:1:35,z(1:36),'b');
stem(36:1:71,z(37:72),'r');
stem(71:1:100,z(72:101),'g');
xlabel('time');
ylabel('amplitude');
title(sprintf('period is 1/36'))