An unambiguous mathematical definition is given by Borwein, Borwein and Taylor by means of analytic continuation of an absolutely convergent series.
The Constant Gardener | Pierre-Constant Budin | The Constant Gardener (film) | Planck constant | André Marie Constant Duméril | Constant Permeke | Benjamin Constant | Constant Lambert | Saint-Constant, Quebec | Planck's constant | Marius Constant | Jean-Joseph Benjamin-Constant | Emmanuel Constant | Dissociation constant | Constant Pressure System | Wilferd Madelung | Man of Constant Sorrow | Georg Hans Madelung | Faraday constant | Constant Vanden Stock Stadium | Constant Mews | Constant Lievens | Constant Chevillon | time constant | Susan Constant | Stefan–Boltzmann constant | solar constant | Saint-Constant, Cantal | Saint-Constant | Robbins constant |
The Ewald summation was developed by Paul Peter Ewald in 1921 (see References below) to determine the electrostatic energy (and, hence, the Madelung constant) of ionic crystals.