Bug in Sum[] or in funtion definitions?

*To*: mathgroup at smc.vnet.net*Subject*: [mg90086] Bug in Sum[] or in funtion definitions?*From*: lehin.p at gmail.com*Date*: Sat, 28 Jun 2008 05:53:23 -0400 (EDT)

Hello The Sum[] seems to ignore special cases of a function. Try the following: c[n_] := k cc^n; c[1] := cc; Sum[c[m], {m, 1, Infinity, 1}] // FullSimplify c[1] + Sum[c[m], {m, 2, Infinity, 1}] // FullSimplify Sum[k cc^n, {n, 1, Infinity, 1}] // FullSimplify c[1] Obviously the special case c[1] := cc is completely ignored by Sum[]. As I understand this is a bug in the Sum[] or in internal work with function definitions. The corresponding pages of the Documentation are: tutorial/MakingDefinitionsForFunctions and tutorial/TheOrderingOfDefinitions