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format of "Solve" output

• To: mathgroup at smc.vnet.net
• Subject: [mg59923] format of "Solve" output
• From: Ed Peschko <esp5 at mdssdev05.comp.pge.com>
• Date: Thu, 25 Aug 2005 06:34:33 -0400 (EDT)
• References: <200508190831.EAA27442@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

hey all,

I had a simple question that I can't find a simple answer for in the docs:

When you solve an equation using 'Solve', it comes out in the format:

{{ x -> a+b, y ->  2 a + b}}

However, when you try to transform the equations for use in FindInstance, 
say by using:


	Fold[And, 1, Apply[Equal, %25[[1]], {1}]]

you get:

	"x" == "a" + "b" && "y" + 2 "a" + "b"

In other words, variables lose their variableness. So, when you
plug the results into, say, FindInstance it complains that "a" is not
a variable.

Is there any reason for this? And how can you turn the character strings
back into variables?

Thanks,

Ed

• Follow-Ups:
  • Re: format of "Solve" output
    • From: "benshimo@bgumail.bgu.ac.il" <bsyehuda@gmail.com>

• References:
  • Nested Lists, Definition and Evaluation.
    • From: "Alexander" <beginning.physst@mail.ru>