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Re: Strange behavior of Simplify

• To: mathgroup at smc.vnet.net
• Subject: [mg40166] Re: Strange behavior of Simplify
• From: "J.L.Garrido" <garrido at ruth.upc.es>
• Date: Tue, 25 Mar 2003 03:01:36 -0500 (EST)
• References: <b5jtgf$mah$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

En/Na Selwyn Hollis ha escrit:

> I've just run across the following strange behavior of Simplify.
> (Using Mathematica 4.1.5, Mac OS X).
>
> These first two commands work as expected:
>
>         Simplify[Exp[2*n*(Log[1 + t] - Log[1 - t])]]
>
>                        (1 - t)^(-2*n) (1 + t)^(2*n)
>
>         Simplify[Exp[n^2*(Log[1 + t] - Log[1 - t])]]
>
>                        (1 - t)^(-n^2) (1 + t)^(n^2)
>
> But Simplify refuses to do anything with this:
>
>         Simplify[Exp[2*n^2*(Log[1 + t] - Log[1 - t])]]
>
>                       Exp[2*n^2*(Log[1 + t] - Log[1 - t])]
>
> Can anyone shed some light here?  By the way, FullSimplify does the
> same thing.
>
> -----
> Selwyn Hollis
> http://www.math.armstrong.edu/faculty/hollis



expr1 = Exp[2*n*(Log[1 + t] - Log[1 - t])];
Simplify[expr1 /. Log[a_] - Log[b_] -> Log[a/b]]
((1 + t)/(1 - t))^(2*n)



expr2 = Exp[2*n^2*(Log[1 + t] - Log[1 - t])];
Simplify[expr2 /. Log[a_] - Log[b_] -> Log[a/b]]
((1 + t)/(1 - t))^(2*n^2)