Bug? Wrong result from infinite sum.
- To: mathgroup at smc.vnet.net
- Subject: [mg49615] Bug? Wrong result from infinite sum.
- From: Ben <serpent11 at hotmail.com>
- Date: Sat, 24 Jul 2004 03:48:36 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
I'm trying to get Mathematica to evaluate Poisson brackets for me, but I am encountering a problem where the sum returns the wrong number. Try this: In a new notebook, evaluate: the partial derivative with respect to a[2] of a[1] (returns 0) the partial derivative with respect to a[2] of a[2] (returns 1) the partial derivative with respect to a[2] of a[infinity] (returns 0) the sum from n = 1 to 1000 of the derivative with respect to a[2] of a[n] (returns 1) the sum from n = 1 to infinity of the derivative with respect to a[2] of a[n] This final sum returns 0 in Mathematica 4.1, and in Mathematica 5.0, it raises an error, indeterminate expression encountered. If I instead take the limit of the sum from n = 1 to m of the derivative with respect to a[2] of a[n], I get zero regardless of the value I let m approach. Can anyone suggest a workaround or fix for this problem? It could be a bug with Mathematica, or could be that I am doing something technically wrong. Thanks, ~Ben