fourier series - fourier transform

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ebi 2013-10-25

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/103339-fourier-series-fourier-transform

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 2013-10-25

Fourier and Fourier transform, What is the difference between the two?

ebi 2013-10-27

在 MATLAB Online 中打开

 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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Answer 1

Jamie 2013-10-27

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https://ww2.mathworks.cn/matlabcentral/answers/103339-fourier-series-fourier-transform#answer_113354

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

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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 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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