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Re: Help with finding zeros
Posted:
Sep 13, 2010 10:19 AM
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On Sep 13, 9:44 am, "Greg Neill" <gneil...@MOVEsympatico.ca> wrote:
> Robert Adams wrote:
> > I could use a little help trying to solve the following engineering
> > problem (no, I am not a student looking for homework help!)
>
> > I need to find the values of w which cause the following summation to
> > go to zero
>
> > sum (n = 1 to N) of exp(-i*w*ln(n))
>
> > where i is the usual sqrt(-1)
>
> > For a given N, there are infintely many solutions due to the
> > periodicity of exp(-i ...)
> > How do I find these solutions?
>
> > Thanks for any pointers.
>
> > Bob Adams
>
> Have you looked into expanding the exponentials into
> trig form? You'll then have a sum of cos and
> imaginary sin terms which will each have to sum to
> zero separately.- Hide quoted text -
>
> - Show quoted text -
Thanks
Yes, I tried this but it's not simple because the log function causes
the cos and sin terms to not be "reguarly sampled"
Bob
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