Plot Fourier Series on MatLab

Trying to plot the first few terms of my fourier series function but I cant seem to resemble the original function for n values greater than two.

n=[2:2:12]; % define n as only even numbers

for f=1:length(n) % define f
   for Time=1:length(t)
       a_not=1/pi;
       b_n=(1/2)*sin((pi*t(Time))/T);
fourier(Time)=a_not+b_n+sum((2/(pi*(1-n(f)^2)))*cos((n(f)*pi*t(Time))/T));
   end
   figure(2)
   plot(t,fourier,t,y)
   hold on
   
end

[darova]

You don't use ifi statement?

Answer 1

[Asvin Kumar]

Your coefficients are right. The issue is that instead of adding the n-th cosine to the exiting variable ‘fourier’, you were overwriting it. Here’s a simpler, stripped down and vectorized version of your code:

n=2:2:12; % define n as only even numbers 
a_not=2/pi; 
b1 = 0.5; 
fourier = a_not/2*ones(size(t)) +b1*sin(pi*t/T) ; 
  
for f=1:length(n) % define f 
    fourier = fourier + 2 / (pi*(1-n(f)^2)) * cos(n(f)*pi*t/T); 
end 

plot(t,fourier) 

If you’re looking for a simpler way to do this have a look at the example at https://www.mathworks.com/help/curvefit/fourier.html#FitFourierModelsExample-1