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Graphing fequence of the signal

  1. Nov 18, 2013 #1
    Say x(n) = n for 0 <= n < 4 and 0 o.w.

    So X(W) = Sum n=-∞ to ∞ x(n) exp(-inw) = sum from n=0 to 3 nexp(-inw)
    = 0 + exp(-iw) + 2exp(-j2w) + 3 exp(-j3w)

    How would I graph F(W)?


    Also if the signal was continuous x(t) = t for the same interval

    X(W)= integral 0 to 4 texp(-iwt) dy = (4exp(-i4w)/ -iw) - (exp(-iw4) -1)/w^2

    How would I graph F(W) for this?
     
  2. jcsd
  3. Nov 18, 2013 #2

    Simon Bridge

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    You wouldn't - no F(W) has been given.
    You have an X(W) - which seems to be the fourier-series expansion of x(w) or something.
    As it is written, it does not seem to depend on W though - but on w.
    It helps if you say what things are.

    Anyway - if your problem is to graph a sum of complex exponentials - you'd either plot the real and imaginary parts separately or plot the trajectory in the complex plane.

    Again - no F(W) or any indication how it may be related to x or X. Same advise I guess.
     
  4. Nov 18, 2013 #3
    I mean X(F).
     
  5. Nov 19, 2013 #4

    Simon Bridge

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    I don't see any X(F) either.
    What are these things supposed to represent?
     
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