Services & Resources / Wolfram Forums / MathGroup Archive
-----

MathGroup Archive 2010

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: Simplification question

  • To: mathgroup at smc.vnet.net
  • Subject: [mg110396] Re: Simplification question
  • From: Bob Hanlon <hanlonr at cox.net>
  • Date: Wed, 16 Jun 2010 05:40:22 -0400 (EDT)

$Version

7.0 for Mac OS X x86 (64-bit) (February 19, 2009)

eqn = 1/2 Log[(Exp[a + b] + Exp[-a - b])/
      (Exp[-a + b] + Exp[a - b])] ==
   ArcTanh[Tanh[a] Tanh[b]];

eqn // TrigToExp //
 Simplify[#, Element[{a, b}, Reals]] &

True

eqn // TrigToExp // Simplify //
 PowerExpand

True


Bob Hanlon

---- Yaroslav Bulatov <yaroslavvb 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?





  • Prev by Date: Re: How to construct symmetric matrix from just a one
  • Next by Date: Re: How to construct symmetric matrix from just a one half matrix
  • Previous by thread: Re: Simplification question
  • Next by thread: Re: Simplification question