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MathGroup Archive 2007

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Re: Optimisation of FourierCoefficients

  • To: mathgroup at
  • Subject: [mg75232] Re: [mg75198] Optimisation of FourierCoefficients
  • From: Sseziwa Mukasa <mukasa at>
  • Date: Sat, 21 Apr 2007 23:10:16 -0400 (EDT)
  • References: <>

On Apr 20, 2007, at 12:37 AM, Edmund wrote:

> I want to find the minimum of a Fourier-Coefficient as a function  
> of the
> input values.
> FindMinimum[Abs[Fourier[{ y, 1}][[1]]], {y, 2}]
> The actual problem is a little more complicated, but even this simple
> statements gives the error messages I can't understand.
> Fourier::fftl: Argument {y, 1} is not a non-empty list or  
> rectangular array
> \
> of numeric quantities.
> Any suggestion ?

Fourier only works on numeric data hence the message when you try to  
compute the transform of {y,1}.  FindMinimum works on symbolic  
expressions so fixing your expression to evaluate y first would be  
problematic since there will be no y in the result and FindMinimum  
would be unable to compute the gradient.  You need to compute the  
general form of your Fourier Coefficient first, then find the minimum  
of that function,



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