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Re: Re: Strange ReplaceRepeated

  • To: mathgroup at
  • Subject: [mg17173] Re: [mg17114] Re: [mg17037] Strange ReplaceRepeated
  • From: David Withoff <withoff>
  • Date: Sun, 18 Apr 1999 23:53:17 -0400
  • Sender: owner-wri-mathgroup at

> Thanks all, who pointed that FullForm of 
> Infinity is DirectedInfinity[1].
> However if I replace _?NumberQ by _?(NumberQ[#]&)
> then everything works as expected. This is because
> NumberQ[Infinity]-> False.
> According to A. Hayes (do You hear Allan?)
> recommendation (see How-Why74.nb ) both patterns
> should give the same answer. I think this
> behaviour is at least misleading.
> Arturas Acus
> Institute of Theoretical
> Physics and Astronomy
> Gostauto 12, 2600,Vilnius
> Lithuania
> E-mail: acus at
>    Fax: 370-2-225361
>    Tel: 370-2-612906

I'm not sure I understand what you did.  I assume that
this is referring to the example:



which gives an infinite loop. When I instead used


though, I still (as I expected) got an infinite loop.  I would not
expect this sort of difference between _?NumberQ and _?(NumberQ[#]&).
Is that the only change you made?

Dave Withoff
Wolfram Research

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