Re: Simplify[] shortcoming

*To*: mathgroup at smc.vnet.net*Subject*: [mg21570] Re: [mg21525] Simplify[] shortcoming*From*: BobHanlon at aol.com*Date*: Sat, 15 Jan 2000 02:04:12 -0500 (EST)*Sender*: owner-wri-mathgroup at wolfram.com

expr = (3*x + (x - y)*Log[x] + (x - y)*Log[-1 + y/x])/(x - y); expr // Apart // Simplify (3*x)/(x - y) + Log[x] + Log[y/x - 1] Bob Hanlon In a message dated 1/14/2000 4:04:26 AM, gorni at dimi.uniud.it writes: >I have run into a simple expression for which both Simplify and >FullSimplify cannot see an easy simplification: > >expr = (3*x + (x - y)*Log[x] + (x - y)*Log[-1 + y/x])/(x - y); > >You can see that the factors (x-y) cancel out with the denominator. >So you can write expr as > >(3*x)/(x - y) + Log[x] + Log[-1 + y/x] > >which has a LeafCount of 21, while expr scored 34. Nevertheless, >Simplify[] leaves expr as it was. > >FullSimplify[expr] does collect (x-y) in the numerator, but still >the LeafCount is 29. > >My version is Mathematica 4 on MacOS. >