Re: Sum

*To*: mathgroup at smc.vnet.net*Subject*: [mg84259] Re: [mg84202] Sum*From*: Bob Hanlon <hanlonr at cox.net>*Date*: Sun, 16 Dec 2007 05:39:00 -0500 (EST)*Reply-to*: hanlonr at cox.net

Not what you asked for but ... Simplify /@ Collect[Sum[False, {i, 1, n}, {j, 1, n}] + Sum[True - False, {i, 1, n}], False] False (n-1) n+True n Bob Hanlon ---- "Beno=C3=AEt Fr=C3=A9nay" <benoit.frenay at uclouvain.be> wrote: > Hello, > > If I feed Mathematica with the following expression > > *>>> Sum[i == j, {i, 1, n}, {j, 1, n}] > > *then nothing happens : it is not able to evaluate the expression. But= > if I set > > *>>> **n = 100* > > and then feed > > *>>> **Sum[i == j, {i, 1, n}, {j, 1, n}] > > *again, then I receive > > *>>> **9900 False + 100 True* > > Is it possible to obtain > > *>>> **False (-1 + n) n + n^2 True* > > when I feed the above sum? > > Thanks, > > Beno=C3=AEt Fr=C3=A9nay >