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Sum

• To: mathgroup at smc.vnet.net
• Subject: [mg84202] Sum
• From: Benoît Frénay <benoit.frenay at uclouvain.be>
• Date: Thu, 13 Dec 2007 07:05:10 -0500 (EST)

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,

Benoît Frénay