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MathGroup Archive 2004

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Re: Simple question or how Mathematica getting on my nerves.

  • To: mathgroup at smc.vnet.net
  • Subject: [mg45840] Re: Simple question or how Mathematica getting on my nerves.
  • From: bobhanlon at aol.com (Bob Hanlon)
  • Date: Tue, 27 Jan 2004 04:50:33 -0500 (EST)
  • References: <bv2f57$2r$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

NIntegrate[k[f], {f, 0.6214, 0.5242}] does not give the same result as
N[Integrate[k[f], {f, 0.6214, 0.5242}]].  Both are calculations with the same
inexact numbers as input so the resulting precision is determined by both the
precision of the input as well as the sequence of internal operations on that
input.  My choice of words is perhaps not  precise.  That is why I tend to
stick to just providing a Mathematica expression.


Bob Hanlon

In article <bv2f57$2r$1 at smc.vnet.net>, Harold.Noffke at wpafb.af.mil (Harold
Noffke) wrote:

<< Bob:

In your reply to George you wrote ...

> Although NIntegrate works without explicitly increasing the precision.  
> So the precision is impacted by the sequencing of the calculations.
>
> NIntegrate[k[f], {f, 0.6214, 0.5242}]
>
> -0.139838

Can you explain what you meant by "sequencing of the calculations"?  I
calculated the integral shown above after restarting Mathematica, and
I obtained the answer shown above.


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