Calculating Fourier Series Coefficients

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Jay Mayle
Jay Mayle 2013-3-6
回答： Sikha ranjith kumar 2022-6-1
I am trying to compute the trigonometric fourier series coefficients of a periodic square wave time signal that has a value of 2 from time 0 to 3 and a value of -12 from time 3 to 6. It then repeats itself. I am trying to calculate in MATLAB the fourier series coefficients of this time signal and am having trouble on where to begin.
The equation is x(t) = a0 + sum(bk*cos(2*pi*f*k*t)+ck*sin(2*pi*f*k*t))
The sum is obviously from k=1 to k=infinity.
a0, bk, and ck are the coefficients I am trying to find. Thanks for the help.
  1 个评论
omar seraj
omar seraj 2021-11-1
How to plot in Fourier series given a time interval -1.5 to 2.5I need a step by step answer to this problem please

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回答（5 个）

Rick Rosson
Rick Rosson 2013-3-6
编辑：Rick Rosson 2013-3-6
>> doc fft
>> doc real
>> doc imag
http://en.wikipedia.org/wiki/Fourier_series
Youssef Khmou
Youssef Khmou 2013-3-6
编辑：Youssef Khmou 2013-3-6
hi Jay , computing a0 bk and ck is bout theory i think, anyway try :
You have first to construct the original signal "Square(t)" so as to compare it with Fourier approximation :
clear , close all;
Fs=60;
t=0:1/Fs:20-1/Fs;
y=square(t,50);
y(y>0)=2;
y(y<0)=-12;
figure, plot(t,y);
axis ([0 20 -20 10])
% Fourier Series
a0=0;
Fy=zeros(size(t));
N=10;
for n=1:2:N
Fy=Fy+(4/n*pi)*sin(2*pi*n*t/(2*pi));
end
hold on,
plot(t,Fy,'r')
legend(' Square ','Fourier Approx');
Try now to to compute an, and bn and increase the number of iterations N and conclude
You have also to adjust the amplitudes
Kamal Kaushal
Kamal Kaushal 2020-3-1
clear , close all;
Fs=60;
t=0:1/Fs:20-1/Fs;
y=square(t,50);
y(y>0)=2;
y(y<0)=-12;
figure, plot(t,y);
axis ([0 20 -20 10])
% Fourier Series
a0=0;
Fy=zeros(size(t));
N=10;
for n=1:2:N
Fy=Fy+(4/n*pi)*sin(2*pi*n*t/(2*pi));
end
hold on,
plot(t,Fy,'r')
legend(' Square ','Fourier Approx');
Hemang Mehta
Hemang Mehta 2020-10-23
clear , close all;
Fs=60;
t=0:1/Fs:20-1/Fs;
y=square(t,50);
y(y>0)=2;
y(y<0)=-12;
figure, plot(t,y);
axis ([0 20 -20 10])
% Fourier Series
a0=0;
Fy=zeros(size(t));
N=10;
for n=1:2:N
Fy=Fy+(4/n*pi)*sin(2*pi*n*t/(2*pi));
end
hold on,
plot(t,Fy,'r')
legend(' Square ','Fourier Approx');
  2 个评论
Aaron Vargas
Aaron Vargas 2020-12-9
hello , is there any chance that you can explain to me the variables and how it works ? im stuck in a homework for college
Rik
Rik 2022-3-31
Comment posted as flag by Hariharan Hariharan:
need the flowof code for case study

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Sikha ranjith kumar
x(t)=cos(50t)

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