Re: Re: Simplify problems for checking easy equalities...

*To*: mathgroup at smc.vnet.net*Subject*: [mg53938] Re: [mg53886] Re: Simplify problems for checking easy equalities...*From*: yehuda ben-shimol <benshimo at bgu.ac.il>*Date*: Fri, 4 Feb 2005 04:12:21 -0500 (EST)*References*: <ctnhah$erh$1@smc.vnet.net> <200502021125.GAA28962@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Kevin, note that for example Log[x^n] - n*Log[x] /. {n -> -4, x -> -2} will return 4*(I*Pi + Log[2]) - Log[16] certainly not 0 yehuda Kevin J. McCann wrote: >David, > >While your approach works, the identity is true regardless of the values >of x and n; so, it is curious that Simplify does not get it for the more >general case. > >Kevin > >David Park wrote: > > >>Cyrus, >> >>Include the proper assumptions in the Simplify statement. >> >>Simplify[Log[x^n] - n*Log[x], n \[Element] Integers && x > 0] >>0 >> >>David Park >>djmp at earthlink.net >>http://home.earthlink.net/~djmp/ >> >>From: Cyrus Erik Eierud [mailto:cyruserik at tele2.se] To: mathgroup at smc.vnet.net >> >> >To: mathgroup 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 >>

**References**:**Re: Simplify problems for checking easy equalities...***From:*"Kevin J. McCann" <kjm@KevinMcCann.com>