Re: format of "Solve" output
- To: mathgroup at smc.vnet.net
- Subject: [mg59934] Re: [mg59923] format of "Solve" output
- From: "benshimo at bgumail.bgu.ac.il" <bsyehuda at gmail.com>
- Date: Fri, 26 Aug 2005 04:53:24 -0400 (EDT)
- References: <200508190831.EAA27442@smc.vnet.net> <200508251034.GAA10188@smc.vnet.net>
- Reply-to: benshimo at bgumail.bgu.ac.il
- Sender: owner-wri-mathgroup at wolfram.com
Hi,
replacing your Out[25] with sol
that is
sol={{x -> a + b, y -> 2 a + b}};
Then there is no way that
Fold[And, 1, Apply[Equal,sol[[1]], {1}]]
will generate strings as you described.
Actualy it generates,
1 && x == a + b && y == 2 a + b
and FindInstance cannot process this
yehuda
On 8/25/05, Ed Peschko <esp5 at mdssdev05.comp.pge.com> wrote:
>
> 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
>
>
- References:
- Nested Lists, Definition and Evaluation.
- From: "Alexander" <beginning.physst@mail.ru>
- format of "Solve" output
- From: Ed Peschko <esp5@mdssdev05.comp.pge.com>
- Nested Lists, Definition and Evaluation.