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I'm trying to plot a Fourier transform of solution of differential equation. I have tried with:

Plot[Evaluate@
  Abs[FourierTransform[
    Re@Evaluate[
      p[t] /. NDSolve[{p'[s] == 1 + (-1.3 + I*10 + p[s])*p[s], 
         p[0] == 0}, p, {s, 0, 10}, MaxSteps -> 100000]], 
    t, \[Omega]]], {\[Omega], 0, 100}, PlotRange -> All]

without success.

What am I doing wrong?

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The "?" button in the edit box gives tips on formatting, such as how to format code. – Michael E2 Feb 28 at 13:21
3  
Why not use Fourier? ff = p[t] /. NDSolve[{p'[s] == 1 + (-1.3 + I*10 + p[s])*p[s], p[0] == 0}, p, {s, 0, 10}, MaxSteps -> 100000][[1]] and Table[ff, {t, 0, 10, 10/256}] // Fourier // Abs // Rest // Flatten // ListLogPlot[#, PlotRange -> All] & – chris Feb 28 at 13:34

1 Answer

up vote 1 down vote

You can solve the equation analytically :

sol[s_] = DSolve[{p'[s] == 1 + (-13/10 + I*10 + p[s])*p[s], p[0] == 0}, p[s], {s}][[1, 1, 2]]
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But an analytical Fourier transform for the function seems to be still impossible? – xzczd Feb 28 at 13:57
1  
I think so; also notice the function flattens to a constant for large argument. – b.gatessucks Feb 28 at 14:02
Oh, that's interesting! – xzczd Feb 28 at 14:17

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