Re: format of "Solve" output
- To: mathgroup at smc.vnet.net
- Subject: [mg59941] Re: format of "Solve" output
- From: "Jens-Peer Kuska" <kuska at informatik.uni-leipzig.de>
- Date: Fri, 26 Aug 2005 04:53:30 -0400 (EDT)
- Organization: Uni Leipzig
- References: <200508190831.EAA27442@smc.vnet.net> <dek84b$a8k$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Hi,
I can't understand your problem because
res = {{ x -> a + b, y -> 2 a + b}};
eqns = Fold[And, True, Apply[Equal, res[[1]],
{1}]];
FindInstance[eqns, {x, y, a, b}]
work fine.
Regards
Jens
"Ed Peschko" <esp5 at mdssdev05.comp.pge.com> schrieb
im Newsbeitrag news:dek84b$a8k$1 at smc.vnet.net...
| 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>
- Nested Lists, Definition and Evaluation.