Question about evaluation with Sum
- To: mathgroup at smc.vnet.net
- Subject: [mg19587] Question about evaluation with Sum
- From: CORNIL Jack Michel <jmcornil at club-internet.fr>
- Date: Sat, 4 Sep 1999 01:34:25 -0400
- Sender: owner-wri-mathgroup at wolfram.com
Hello,
I have a big problem of evaluation with the function Sum.
With the very simple following example,
p=k
Sum[p,{k, 1, n}]
p k
Sum[Evaluate[p], {k, 1, n}]
1
- n (1+n)
2
Sum[p,{k, 1, 5}]
15
how can I explain my students that
in the first case p is left unevaluate and it needs Evaluate,
in the last case p is evaluate correctly ?
I do not understand how the "Attributes" of Sum can explain this.
Thank You in advance
Jack Michel CORNIL
Versailles FRANCE