Re: Simplify problems for checking easy equalities...

*To*: mathgroup at smc.vnet.net*Subject*: [mg53860] Re: Simplify problems for checking easy equalities...*From*: "Drago Ganic" <drago.ganic at in2.hr>*Date*: Tue, 1 Feb 2005 04:08:10 -0500 (EST)*References*: <cti5nd$8n2$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Hi Cyrus, use assumptions! The simplification qou expect is not generally valid. Simplify or Refine are enough for the elementary functions! FullSimplify[Log[x^n] - n Log[x], n \[Element] Integers && x > 0] 0 Simplify[Log[x^n] - n*Log[x], n \[Element] Integers && x > 0] 0 Refine[Log[x^n] - n*Log[x], n \[Element] Integers && x > 0] 0 Those assumptions are used implicity in the unary function PowerExpand: Log[x^n] - n*Log[x] // PowerExpand 0 Greetings, Drago "Cyrus Erik Eierud" <cyruserik at tele2.se> wrote in message news:cti5nd$8n2$1 at smc.vnet.net... > Please Help! > > Thanks for all great answers I've already found here! > My problem is that I can not simplify what to me seems as a very > simple equality task. This is what I want Mathematica to return zero > for: > > in[1]:= FullSimplify[Log[x^n] - n*Log[x]] > > out[1]= -n Log[x] + Log[x^n]) > > I have used Simplify to check equalities, but the one above (and many > other equations similar to the one above) just don't simplify. Am I > doing anything wrong or does anyone know of a better way to check > equalities? > > Appreciate any help, > Cyrus Eierud, Student > cyruserik at tele2.se >