• To: mathgroup at smc.vnet.net
• Subject: [mg56938] Re: NSum: badly missed Option
• From: "antononcube" <antononcube at gmail.com>
• Date: Tue, 10 May 2005 03:43:02 -0400 (EDT)
• References: <200505070816.EAA20223@smc.vnet.net><d5j5ob\$qf3\$1@smc.vnet.net> <d5kb13\$2at\$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```Alan wrote:
> "Chris Chiasson" <chris.chiasson at gmail.com> wrote in message
> news:d5j5ob\$qf3\$1 at smc.vnet.net...
> > Try SetOptions on NIntegrate before the NSum call.
>
> Excellent. Thanks for the solution!
>
> regards,
> alan

Nested Method option can be used in NSum.

For example:

In[1]:= NSum[1/(x20*Sin[x]^2), {x, 2, Infinity}, Method -> NIntegrate]

NIntegrate::ncvb:
NIntegrate failed to converge to prescribed accuracy after 7
recursive bisections in x near x = 18.8764.

Out[1]= 1.16782 10^-6

In[2]:= NSum[1/(x20*Sin[x]^2), {x, 1, Infinity}, Method -> {NIntegrate,
MaxRecursion -> 100}]

NIntegrate::slwcon:
Numerical integration converging too slowly; suspect one of the
following:
singularity, value of the integration being 0, oscillatory
integrand, or
insufficient WorkingPrecision. If your integrand is oscillatory try
using
the option Method->Oscillatory in NIntegrate.

Out[2]= 1.41228

Anton Antonov
Wolfram Research, Inc.

```

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