Re: Inverse function warnings

*To*: mathgroup at smc.vnet.net*Subject*: [mg99174] Re: Inverse function warnings*From*: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>*Date*: Wed, 29 Apr 2009 06:05:59 -0400 (EDT)*Organization*: Uni Leipzig*References*: <gt90og$l55$1@smc.vnet.net>*Reply-to*: kuska at informatik.uni-leipzig.de

Hi, because Table[3^(2 x) - 12 (3^x) + 27 == 0 /. x -> 1 + 2 I*Pi*any/Log[3], {any, 1, 10}] gives True for all any and this is only found by Reduce[] and not by Solve[]. Use Quiet[ Solve[3^(2 x) - 12 (3^x) + 27 == 0, x] ] if you wish to ignore an infinite number of solutions. Regards Jens davef wrote: > When I execute this in Mathematica 7: > > Solve[3^(2 x) - 12 (3^x) + 27 == 0, x] > > I get this: > > Solve::ifun: Inverse functions are being used by Solve, so some solutions may not be found; use Reduce for complete solution information. >> > > {{x->1},{x->2}} > > > 1 amd 2 are proper solutions but is it possible to avoid the warning? > > If I use Reduce: > > Reduce[3^(2 x) - 12 (3^x) + 27 == 0, x] > > I get a set of 1 and 2 added to some imaginary number terms that I don't quite understand. > > I guess my question is: why would the use of inverse functions be so unreliable a solution as to necessitate a warning? And in the interest of clean output, can the warning be supressed other than by deleteing the cell? > > Thanks >