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Topic: Help with finding zeros
Replies: 7   Last Post: Sep 14, 2010 3:35 PM

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 Bob Adams Posts: 55 Registered: 12/13/04
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

Date Subject Author
9/13/10 Bob Adams
9/13/10 Greg Neill
9/13/10 Rod
9/13/10 Bob Adams
9/13/10 Gerry Myerson
9/13/10 Bob Adams
9/14/10 Robert Israel
9/14/10 Bob Adams

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