Re: Solve yields unreal solutions, NSolve yields real solutions
- To: mathgroup at smc.vnet.net
- Subject: [mg58287] Re: Solve yields unreal solutions, NSolve yields real solutions
- From: Peter Pein <petsie at dordos.net>
- Date: Sun, 26 Jun 2005 01:33:49 -0400 (EDT)
- References: <d9issf$cps$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Mukhtar Bekkali schrieb:
> I thought NSolve is the same as Solve just numeric. The below code
> gives real answers, replacing NSolve with Solve in the last line
> generates Unreal results. I do not understand why.
>
> \!\(\*
> RowBox[{\(Clear["\<Global`*\>"]\), "\n", \(Remove["\<Global`*\>"]\),
...
> "\[IndentingNewLine]", \(NSolve[FOCB \[Equal] 0, T\_b]\)}]\)
>
I do not use RealOnly, so I can not tell you exactly what's going on,
but I *guess* the intermediate complex numbers vanish due to RealOnly.
Solve gives me only Reals in this case:
sol = RootReduce[Solve[FOCB == 0, Subscript[T, b]]]];
N[sol]
{{Subscript[b, 1] -> 1.8560333600623977,
Subscript[b, 2] -> 9.206972531099007},
{Subscript[b, 1] -> 0.3071686114422483,
Subscript[b, 2] -> 0.9103220918432908},
{Subscript[b, 1] -> -8.463201971504645,
Subscript[b, 2] -> -0.8172946229422982}}
I *guess* the intermediate complex numbers vanish due to RealOnly.
--
Peter Pein
Berlin