Re: Simplify and FullSimplify

*To*: mathgroup at smc.vnet.net*Subject*: [mg58559] Re: Simplify and FullSimplify*From*: Bill Rowe <readnewsciv at earthlink.net>*Date*: Thu, 7 Jul 2005 05:35:48 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

On 7/6/05 at 3:11 AM, fizzycist at knology.net (fizzy) wrote: >A result of a calculation I was doing generated this expression.... >q-q Exp[-a x] + c Exp[-a x] >naturally my next step was Simplify and I thought I'd get the >Exp[- ax] collected.....to my complete surprize I got the >following: >Exp[-a x] (c + (-1+ Exp[a x]) q >How on Earth did Mathematica come up with this? I checked >FullSimplify which did collect Exp[-a x].... >On re-reading my question before I submitted it, I see that with >Simplify Mathematica 'collected' using Exp[- a x] q.....of course, >visually this expression seems quite complex and would seem to take >much more 'thinking' to get ......why do Simplify and FullSimplify >have such a vast difference in what is considered 'Simpler'? The issue isn't a difference between what is considered simpler by Simplify and FullSimplify. Instead, FullSimplify tries more transformations than Simplify. For any method to simplify an expression, there will always be a trade between execution time and results. Simplify tries fewer transformations, enhancing execution time at the cost of not finding a transformation that may make the expression simpler. FullSimplify tries more transformations, significantly increasing the probability of finding a transformation that leads to a simpler expression at the cost of execution time. -- To reply via email subtract one hundred and four