According to these pages http://jeff560.tripod.com the word ‘pole’ was first used in *Théorie des fonctions elliptiques*.

English translation (of course using google), “When u is holomorphic function in a certain part of the plan, except at a point z1, where it becomes infinite, so however that the function remains 1/u holomorphic in the neighborhood of this point, we say that this is a pole or infinite the function u.”

In their memoirs they have mentioned that pole is ‘un infini du degré fini’- An infinity of finite degree.

However, they do not explain why they have used the word ‘pole’. English speaking people give a intuitive explanation, “it was because if you plot, or envision plotting, the surface z = |f(x + iy)|, at poles of f, the surface, if you imagine it sitting over the xy plane, looks like it is being supported by a really tall pole. Like a circus tent.”[2] That does not goes well with ‘French’ and ‘German’ since their idea of ‘pole’ is slightly different (not related with ‘pillar’). Besides the inventors of this word were French. Perhaps an explanation that would also make sense in French and German is that the value of a function at a pole is equal to infinity, the North pole of the Riemann sphere.

However, if one look at this figure, it is not at all hard to agree with ‘circus tent’ theory. http://en.wikipedia.org/wiki/File:Jahnke_gamma_function.png

Renteln and Dundes (2005) give the following (bad) mathematical jokes about poles:[3]

Q: What’s the value of a contour integral around Western Europe? A: Zero, because all the Poles are in Eastern Europe.

Q: Why did the mathematician name his dog “Cauchy?” A: Because he left a residue at every pole.

REF :[1] http://visualiseur.bnf.fr/Visualiseur?Destination=Gallica&O=NUMM-99571

[2] http://mathoverflow.net/questions/39538/what-is-the-naming-reason-of-poles-in-complex-analysis

[3] Renteln, P. and Dundes, A. “Foolproof: A Sampling of Mathematical Folk Humor.” *Notices Amer. Math. Soc.* **52**, 24-34, 2005.

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## About Dilawar

Graduate Student at National Center for Biological Sciences, Bangalore.