Search All of the Math Forum:
Views expressed in these public forums are not endorsed by
NCTM or The Math Forum.


Math Forum
»
Discussions
»
sci.math.*
»
sci.math
Notice: We are no longer accepting new posts, but the forums will continue to be readable.
Topic:
Help with finding zeros
Replies:
7
Last Post:
Sep 14, 2010 3:35 PM




Re: Help with finding zeros
Posted:
Sep 13, 2010 10:19 AM


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



