Assisting FullSimplify

*To*: mathgroup at smc.vnet.net*Subject*: [mg56143] Assisting FullSimplify*From*: "Hugh Goyder" <h.g.d.goyder at cranfield.ac.uk>*Date*: Sat, 16 Apr 2005 03:53:17 -0400 (EDT)*Organization*: University of Warwick, UK*Sender*: owner-wri-mathgroup at wolfram.com

I started with the expression e1 below. FullSimplify does not make any progress in making it simpler. By a mixture of working on parts of the expression, luck and physical reasoning I worked out that the expression is the same as that given in e2. (For example I knew the expression should be real). Is there anyway that I could have directed FullSimplify to get from e1 to e2, by for example setting options? (Cutting and pasting the code below into a notebook will make it readable. It may then be evaluated.) Thanks Hugh Goyder e1 = (4*I* E^(I*(a + b)*k)*(-E^(2*I*a*k) + E^(2*I*(1 + ar)*k)))/(E^(2*I*(1 + a + ar)*k)*(-2 + Sr) + E^(2*I*(a + b)*k)*(-2 + Sr) - E^(4*I*a*k)*Sr + E^(2*I*(1 + ar)*k)*Sr + E^(2*I*(2*a + b)*k)*Sr - E^(2*I*(1 + ar + b)*k)*Sr - E^(2*I*a*k)*(2 + Sr) - E^(2*I*(1 + a + ar + b)*k)*(2 + Sr)) e2 = -(Sin[(1 - a + ar)*k]/((-Cos[(1 + ar)*k])*Cos[b*k] + Sr*Cos[a*k]*Sin[(1 - a + ar)*k]*Sin[b*k])) FullSimplify[e1] FullSimplify[e1 == e2] LeafCount[e1] LeafCount[e2]

**Follow-Ups**:**Re: Assisting FullSimplify***From:*Chris Chiasson <chris.chiasson@gmail.com>