Re: how to test if 2 expressions are the same? Mathematica 5.0

*To*: mathgroup at smc.vnet.net*Subject*: [mg46096] Re: how to test if 2 expressions are the same? Mathematica 5.0*From*: bobhanlon at aol.com (Bob Hanlon)*Date*: Fri, 6 Feb 2004 04:15:19 -0500 (EST)*References*: <bvt135$oj5$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Use Equal (==); however, you will also frequently have to use Simplify or FullSimplify. 1-Sin[x]^2 == Cos[x]^2 1 - Sin[x]^2 == Cos[x]^2 %//Simplify True You may also have to state Assumptions that would make the equality True a*Log[x] == Log[x^a] // Simplify a*Log[x] == Log[x^a] Simplify[%, {Element[{a,x}, Reals], x>0}] True Sometimes there are shortcuts using PowerExpand; however, you need to be sure that the implied assumptions hold. a*Log[x] == Log[x^a] // PowerExpand True Bob Hanlon In article <bvt135$oj5$1 at smc.vnet.net>, nma124 at hotmail.com (steve_H) wrote: << many times, I want to find if there is a way to obtain one expression from another by tranformation. for example, we know that 1-sin^2(x) = cos^2(x), and a*log(x)=log(x^a), etc.., but sometimes this does not seem to work using SameQ: SameQ[a Log[x], Log[x^a] ] False I tried MatchQ and that also gives False. what is the right way to do these things in Mathematica? I checked the on-line help, and can't seem to see the right command for this.