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Re: Help with finding zeros
Posted:
Sep 13, 2010 11:37 AM
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On Sep 13, 10:01 am, "Rod" <rodrodrod...@hotmail.com> wrote:
> "Greg Neill" <gneil...@MOVEsympatico.ca> wrote in message
>
> news:BUpjo.55715$iw4.28826@unlimited.newshosting.com...
>
>
>
>
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> > 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.
>
> That's my approach as well
> Wouldn't w have to be complex to achieve both series being zero.
>
> Is this not a truncated zeta function?- Hide quoted text -
>
> - Show quoted text -
Yes, this is related to the zeta function.
I was hoping to to find a solution where w is real, but this may not
be possible as you point out
Bob
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