Re: [R] Off topic --- help in locating a source.

From: Gabor Grothendieck <ggrothendieck_at_gmail.com>
Date: Thu 18 May 2006 - 07:41:10 EST

If a web site is suffiicent then:
http://functions.wolfram.com/ElementaryFunctions/Cos/23/02/

On 5/17/06, Rolf Turner <rolf@math.unb.ca> wrote:
> Apologies for the off-topic question; as usual I'm trying to draw
> upon the unparalleled knowledge and sagacity of the r-help list.
> Please reply off-list if you can help me out.
>
> A collaborator of mine found a formula we need, on sheets which he had
> photocopied out of a book, some years ago. He cannot remember which
> book (he's getting to be as senile and forgetful as I am, poor
> bloke!). He thinks it was (and it appears to have been) a large
> encylopedic tome devoted to extensive tables of formulae, integrals
> and series, and stuff like that.
>
> The formula in question is
>
> oo 1 1 1
> SUM --- cos(k*x) = --- ln (----------------) 0 < x < 2*pi .
> k=1 k 2 2*(1 - cos(x))
>
> (I.e. the right hand side is a function whose Fourier coefficients
> are 1/k, k > 0).
>
> Note that ``oo'' is my attempt to render the infinity symbol in
> ASCII.
>
> Does anyone know of a source where this formula may found/cited?
> (It doesn't *have* to be the same source from which my collaborator
> originally copied it!) It must be well-known/in lots of books,
> mustn't it? Said he, hopefully.
>
> Thanks for any assistance.
>
> cheers,
>
> Rolf Turner
> rolf@math.unb.ca
>
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https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Thu May 18 08:01:46 2006

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