Re: format of "Solve" output
- To: mathgroup at smc.vnet.net
- Subject: [mg59932] Re: [mg59923] format of "Solve" output
- From: Bob Hanlon <hanlonr at cox.net>
- Date: Fri, 26 Aug 2005 04:53:23 -0400 (EDT)
- Reply-to: hanlonr at cox.net
- Sender: owner-wri-mathgroup at wolfram.com
expr={{x->a+b,y->2 a+b}};
Apply[Equal,expr[[1]],{1}]
{x == a + b, y == 2*a + b}
Bob Hanlon
>
> From: Ed Peschko <esp5 at mdssdev05.comp.pge.com>
To: mathgroup at smc.vnet.net
> Date: 2005/08/25 Thu AM 06:34:33 EDT
> Subject: [mg59932] [mg59923] format of "Solve" output
>
> 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
>
>