Re: NSum working on Re[ ]
- To: mathgroup at smc.vnet.net
- Subject: [mg43090] Re: NSum working on Re[ ]
- From: Paul Abbott <paul at physics.uwa.edu.au>
- Date: Tue, 12 Aug 2003 04:43:04 -0400 (EDT)
- Organization: The University of Western Australia
- References: <bgv8md$58b$1@smc.vnet.net> <bh2685$hnq$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
In article <bh2685$hnq$1 at smc.vnet.net>,
Mathijs Romans <m.w.j.romans at phys.uu.nl> wrote:
> While I was trying to focus on the problem, I gave a simplified version
> of the issue. For my problem, I do not think there is a workaround:
>
> NSum[(1 + Re[Sqrt[1 - I n]]) / ((n + Im[Sqrt[1 - I n]])^2 + (1 +
> Re[Sqrt[1 - I n]])^2) , {n, 1, Infinity}]
>
> gives a similar error, due to the derivative of Re[] being unknown...
Simplification of the summand prior to summation seems to work fine:
Simplify[ComplexExpand[(Re[Sqrt[1 - I n]] + 1)/
((Re[Sqrt[1 - I n]] + 1)^2 + (n + Im[Sqrt[1 - I n]])^2),
TargetFunctions -> {Re, Im}]]
NSum[%, {n, 2, Infinity}]
Cheers,
Paul
--
Paul Abbott Phone: +61 8 9380 2734
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