Re: Simplification question

*To*: mathgroup at smc.vnet.net*Subject*: [mg110398] Re: Simplification question*From*: Simon <simonjtyler at gmail.com>*Date*: Wed, 16 Jun 2010 05:40:45 -0400 (EDT)*References*: <hv76mt$k6e$1@smc.vnet.net>

It might be that Mathematica is having troubles because of the branch cuts in the inverse functions. If you take Tanh of both sides, then it becomes easier... On Jun 15, 4:30 pm, Yaroslav Bulatov <yarosla... at gmail.com> wrote: > I'd like to verify that the following expression is true for a,b real. > It seems to hold numerically. > > 1/2 Log[(Exp[a + b] + Exp[-a - b])/(Exp[-a + b] + Exp[a - b])] == > ArcTanh[Tanh[a] Tanh[b]] > > I tried Reduce and combinations of TrigToExp/Simplify with no luck, > any suggestions?