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

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 Rod Posts: 521 Registered: 12/7/04
Re: Help with finding zeros
Posted: Sep 13, 2010 10:01 AM

"Greg Neill" <gneillRE@MOVEsympatico.ca> wrote in message
news:BUpjo.55715\$iw4.28826@unlimited.newshosting.com...
>> 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.
>>

>
> 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?

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