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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" <> 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 -


Yes, I tried this but it's not simple because the log function causes
the cos and sin terms to not be "reguarly sampled"


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