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