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Groups > comp.soft-sys.math.mathematica > #1954

Re: Limit[f[x], x->a] vs. f[a]. When are they equal?

From Richard Fateman <fateman@cs.berkeley.edu>
Newsgroups comp.soft-sys.math.mathematica
Subject Re: Limit[f[x], x->a] vs. f[a]. When are they equal?
Date 2011-04-28 10:35 +0000
Organization Steven M. Christensen and Associates, Inc and MathTensor, Inc.
Message-ID <ipbfti$ae9$1@smc.vnet.net> (permalink)
References <ip6834$bmt$1@smc.vnet.net>

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On 4/26/2011 3:51 AM, Andrzej Kozlowski wrote:
.. skipped and snipped...


> and so on. In Mathematica is no sense in taking limits as z ->ComplexInfinity

> without specifying a direction as there is no natural direction.

So the idea of a limit as x->x0  makes no sense if x0 is a member of 
some set of numbers, symbols, whatever.  Maybe the documentation for 
Limit should provide some information on this?

I don't know what you have written previously on this topic and have no 
intention of looking it up.  But in a system which includes 
ComplexInfinity, a concept which unifies at one "place" positive real 
infinity and negative real infinity, it becomes tricky to also have the 
separate values +Infinity and -Infinity.

some of my thoughts are in section 4 of
http://www.cs.berkeley.edu/~fateman/papers/interval.pdf

RJF





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Thread

Re: Limit[f[x], x->a] vs. f[a]. When are they equal? Andrzej Kozlowski <akoz@mimuw.edu.pl> - 2011-04-26 10:51 +0000
  Re: Limit[f[x], x->a] vs. f[a]. When are they equal? Noqsi <noqsiaerospace@gmail.com> - 2011-04-30 09:51 +0000
    Re: Limit[f[x], x->a] vs. f[a]. When are they equal? Richard Fateman <fateman@cs.berkeley.edu> - 2011-05-02 10:51 +0000
  Re: Limit[f[x], x->a] vs. f[a]. When are they equal? Richard Fateman <fateman@cs.berkeley.edu> - 2011-04-28 10:35 +0000
  Re: Limit[f[x], x->a] vs. f[a]. When are they equal? Andrzej Kozlowski <akoz@mimuw.edu.pl> - 2011-04-28 10:36 +0000
  Re: Limit[f[x], x->a] vs. f[a]. When are they equal? Richard Fateman <fateman@eecs.berkeley.edu> - 2011-04-29 11:29 +0000

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