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Homework Help: Fourier Transform

  1. Mar 14, 2013 #1
    1. The problem statement, all variables and given/known data
    See Attachment

    2. Relevant equations

    3. The attempt at a solution

    Ok so in a previous question I worked out fd = e-ipd*2*sinc(pa)/√(2∏), also worked out its fourier transform if that helps.

    Now I really am stuck on the question, any guidance would be appreciated, I don't understand how the function fd is summed over from -N to N, like I say any help to just send me in the right direction would be great.

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  2. jcsd
  3. Mar 14, 2013 #2
    The problem suggests that the function fd should be a function of x, but I don't see an x in your expression.
  4. Mar 15, 2013 #3
    Well the original function was f(x) which was a function of x that I then fourier transformed with limits of x =-a to x=a, this replaced the x's with a's. fd(x) was then a slight variation of the original f(x) function, ultimately I ended up with said function where fd(x) = f(x - d) which transforms to e(-ipd)*f(p) where f(p) was the fourier transform of f(x).
  5. Mar 16, 2013 #4
    I made an issue with the question, not sure how to edit. Anyway f_d(x) = 1/a when |x-d|< a. What I said in the 1st post is actually the fourier transform of this.
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