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Interpolating Data with the Discrete Fourier Transform

  1. Jul 2, 2013 #1
    Hello everyone:

    I have some question using the FFT in matlab for data interpolating. I don't know what the relation between the normal fourier series and the real, image number.

    For example, given a set of measurement data, I can use the curve fitting toolbox to fit a curve.
    The general equation is f(x) = a0 + a1*cos(x*w) + b1*sin(x*w) + a2*cos(2*x*w) + b2*sin(2*x*w) for a a factor 2 fourier series. The a0,a1,b1,a2,b2 and w can be obtained.

    When I use the FFT function, it returns the Fourier transform of each column of the matrix. This matrix has real and imaginary part.

    Are their any relationship between those two results ? if yes, what should I do to convert the FFT results into a normal fourier series format?

    Thank in advance.
     
  2. jcsd
  3. Jul 3, 2013 #2

    mathman

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    Science Advisor
    Gold Member

    Usually when you have a Fourier transform with real and imaginary parts, the real part is the cosine transform and the imaginary part is the sine transform.

    However I am not familiar with the specific algorithm, so I could be completely wrong.
     
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