Question

Generating a square wave This function approximates a square wave by summing a series of sinusoidal functions of various frequencies and amplitudes square n MATLAB write a function that allows the user to choose the number of terms used to approximate the square wave, i.e. input the value of k. Your function should plot the resulting square wave, show the value used for k in the title (note k needs to be converted to a string data type), and plot the FFT all on the same page. SET omega-1 for this exercise. You are the creator for this task, so thinking ahead and knowing that fs is points per unit time set fs in your program to 1000, then your t will be equal to 0: 1/fs: 15]. Now the frequency scale for your fft is [-fs/2 : fs/length(t)-1: fs/2].

Answer 1

The name of the function is my_square and can be called from the command window:

function my_square(k)
w=1;
fs=1000;
t=0:1/fs:15;
f=[-0.5*fs:fs/(length(t)-1):0.5*fs];
x=0;
for i=1:k
x=x+sin(w*t*(2*i-1))/(2*i-1);
end
X=fft(x);
X=fftshift(X);
figure;
subplot(2,1,1);
plot(t,x);
val=int2str(k);
tit=strcat('The plot for k=',val);
title(tit);xlabel('time'),ylabel('Value');
subplot(2,1,2);
plot(f,abs(X));
title('Magnitude Spectrum');xlabel('frequency');ylabel('Magnitude');
end

Now, calling my_square(25) from command window provides the following plot: