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MathGroup Archive 1995

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Re: How do I define a range of a symbol?

  • To: mathgroup at
  • Subject: [mg977] Re: How do I define a range of a symbol?
  • From: Richard J Fateman <fateman at CS.Berkeley.EDU>
  • Date: Thu, 4 May 1995 06:14:35 -0400

> In article <3nkcqm$n02 at>,
> Paul A. Rubin <rubin at> wrote:
> >In article <3nhu1f$7m2 at>, hsvrt at wrote:
> >->Can anyone help me with the following (probably elementary) problem:
> >->
> >->Is it possible to specify a range of a constant, e.g.
> >->
> >->0 < k < Infinity, or
> >->0 < k < 100, or
> >->k not equal to 0
> >->
> >
> >In general, I do not think this is possible.  You can use upvalues to give 
> >Mathematica this sort of information.  For instance, to specify 0 < k < 100 
> >you could use
> >
> >  k /: Greater[ k, 0 ] = True
> >  k /: Less[ k, 100 ] = True
> >
> >There are two fundamental problems with this.  ...
 Paul correctly points out that Mathematica can't do it.
 It is not a trivial problem to solve, and the importance of solving
 it was, I suspect, not apparent to the designers of Mathematica at the
 time the program was being put together. 
 There are some bits and scraps of ranges PRODUCED by programs like
 Integrate, but since the rest of the Mathematica program can't handle
 them, it is not clear that one can do more than print them out for
 the human user to see.
 Richard J. Fateman
 fateman at   510 642-1879

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