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MathGroup Archive 2004

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Re: Number of roots from Solve?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg48496] Re: Number of roots from Solve?
  • From: Bill Rowe <readnewsciv at earthlink.net>
  • Date: Wed, 2 Jun 2004 04:22:04 -0400 (EDT)
  • Sender: owner-wri-mathgroup at wolfram.com

On 6/1/04 at 3:02 AM, akoz at mimuw.edu.pl (Andrzej Kozlowski) wrote:

>There are two reasons why I am sure Solve uses Rationalize.  One,
>less important reason is that  in the example that started this
>thread there are  variables that have real exponents: there are no
>algebraic methods for solving such equations. Threfore they have to
>be converted to rationals. You can also check that NSolve will not
>solve these equations.

>Secondly, Solve depends fundamentally on Groebner basis. Grobener
>basis with non-exact coefficients is a very tricky thing. I think
>Daniel Lichtblau actually implemented something like that in
>NSolve, but certainly not in Solve. So there is no doubt that Solve
>has to rationalize equations to use Groebner basis.

>Finally, your example means nothing more than Solve applies N to
>the final result, as you would expect it to do.

Thanks for the explanation
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