Re: Summation in Mathematica

*To*: mathgroup at smc.vnet.net*Subject*: [mg130611] Re: Summation in Mathematica*From*: Roland Franzius <roland.franzius at uos.de>*Date*: Fri, 26 Apr 2013 04:24:36 -0400 (EDT)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*Delivered-to*: l-mathgroup@wolfram.com*Delivered-to*: mathgroup-outx@smc.vnet.net*Delivered-to*: mathgroup-newsendx@smc.vnet.net*References*: <kl8e4n$on7$1@smc.vnet.net>

Am 24.04.2013 13:02, schrieb Ben Blomberg: > Hello All, > > I am trying to understand a piece of code I found but I am stuck on this > summation. This is part of a larger do loop over n. > > UnderoverscriptBox[\(\[Sum]\), \(m = \(-10\)\), > \(10\)]\(\(eigenfunctionsort[n, j]\)[\([m + 11]\)] > Exp[I*2*\[Pi]*m*x/dp]\)\),{j,1,21}] > > What I mainly do not understand is what is happening with the [m+11]. Is > that being multiplied with eigen function sort with each step in the sum, > or is that simply adding 11 to m at each step in the sum? The piece of code should be read in InputForm Sum[eigenfunctionsort[n, j][[m + 1]] * Exp[2 *\[Pi] *I *m *x /dp], {m, -10, 10}] In FullForm, eigenfunctionsort[n, j][[m + 1]] means Part[eigenfunctionsort[n, j],m+1], the m+1-component of the vector of eigenfunctions probably with quantum numbers n and j. -- Roland Franzius