From: Rolf Turner <rolf_at_math.unb.ca>

Date: Thu 18 May 2006 - 05:27:16 EST

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 05:31:58 2006

Date: Thu 18 May 2006 - 05:27:16 EST

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 ______________________________________________R-help@stat.math.ethz.ch mailing list

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 05:31:58 2006

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