Simplification and Arg[]

*To*: mathgroup at smc.vnet.net*Subject*: [mg66593] Simplification and Arg[]*From*: Andrew Moylan <andrew.moylan at anu.edu.au>*Date*: Sun, 21 May 2006 22:30:37 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

Should Mathematica be able to simplify the following expression? (It is easily seen to be zero under the given condition, x > 0.) FullSimplify[ Arg[1 + I * x] + Arg[1 - I * x], {x > 0} ] In particular, I would have expected the following to yield ArcTan[b / a], from which the above expression is easily reduced to zero: FullSimplify[ Arg[a + I b], {a > 0, b > 0} ] Any ideas? Cheers, Andrew P.S. Apologies if I have sent this twice; my original message seems not to have worked.

**Follow-Ups**:**Re: Simplification and Arg[]***From:*Andrzej Kozlowski <akoz@mimuw.edu.pl>