Re: Re: Just another bug in MMA 3.0

*To*: mathgroup at smc.vnet.net*Subject*: [mg7637] Re: [mg7491] Re: [mg7431] Just another bug in MMA 3.0*From*: Alistair.Windsor at vuw.ac.nz (Alistair.Windsor at vuw.ac.nz)*Date*: Fri, 20 Jun 1997 16:16:10 -0400 (EDT)*Organization*: Victoria University of Wellington, New Zealand*Sender*: owner-wri-mathgroup at wolfram.com

In article <5nqru3$l5j at smc.vnet.net>, koehler at math.uni-bonn.de (Kai Koehler) wrote: > In article <5nfpv3$5qp at smc.vnet.net>, Paulo Mouat <mouat at mail.telepac.pt> wrote: > > > Kai Koehler wrote: > > > > Sum[Sum[Log[Log[k+j]],{k,1,n}],{j,1,5}] > > > > > > gives > > > > > > 5*Sum[Log[Log[k + j]], {k, 1, n}]. > > > If you want to do a multiple sum, the input should read > > > > Sum[Log[Log[k+j]],{k,1,n},{j,1,5}] > > > > What you have typed is a simple sum over k with a function that has an > > unknown j. The j on the outer Sum is a dummy variable, with no > > relation to the one in Log[k+j]. > > > > This is not a bug. Mathematica simply interpreted what you did type, > > which is not quite what you intended to do. > > If this where true, It is. > Sum[Sum[j,{k,1,n}],{j,1,5}] > > should give 5 n j as output. No have a look at what he typed again. =>Sum[Log[Log[k+j]],{k,1,n},{j,1,5}] <=. Here both iterator variables appear in the outer level of the Nested Sums. In what you hve typed they appear in separate levels. If you were to write Sum[Sum[j],{k,1,n},{j,1,5}] you would indeed get 5 n j. There is no bug here. The iterator j is a local variable assign a unique hash and is hence different from the j inside the sum. >Instead you get 15 n (correctly, IMHO). > Also, in StandardForm, the difference between -- Alistair Windsor Mathematics Graduate Student Victoria University of Wellington New Zealand