fourier series - fourier transform

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ebi
ebi 2013-10-25
编辑： Jamie 2013-10-28
i want fourier and fourier transform of the " u " .
t = 0:0.001:0.334;
u = ones(size(t)).*(t >= 0).*(t <= 0.02)+zeros(size(t)).*(t > 0.02).*(t < 0.287)+ones(size(t)).*(t >= 0.287).*(t <= 0.307)+zeros(size(t)).*(t > 0.307).*(t <= 0.335);
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Azzi Abdelmalek
Azzi Abdelmalek 2013-10-25
Fourier and Fourier transform, What is the difference between the two?
ebi
ebi 2013-10-27
for g Fourier is f(t)=a0+sigma(an*cos... ), a=1/T*int(g), ... and Fourier transform is F(w)=integral(g*exp(-iwt)).... .

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回答（1 个）

Jamie
Jamie 2013-10-27
编辑：Jamie 2013-10-27
Hey Ebi,
The choice of fourier transform or fourier series simply depends on whether the signal is periodic or aperiodic.
To obtain the transform
help fft
For the fourier Series - http://www.mathworks.com.au/help/curvefit/fourier.html
Cheers
  2 个评论
ebi
ebi 2013-10-27
yes my signal is load-time signal with T0=0.334(period).for fourier transform we need to define w . how we define w and t? " u " is define in good way to use in fourier transform or fourier series ? the " u " is a simple piecewise function that relate to t.
Jamie
Jamie 2013-10-28
编辑：Jamie 2013-10-28
Hey Ebi, I would be looking at the curve fitting tool (fourier series ~ periodic). From my understanding you're simply attempting to fit a curve to the signal 'u' with elements acos()+ bsin ().. etc. All you need to do is specify the number of terms and apraise the fit.
have a look at the link I pasted above.
Cheers

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