Re: Taking the Arg of a complex number

*To*: mathgroup at smc.vnet.net*Subject*: [mg122117] Re: Taking the Arg of a complex number*From*: "Dr. Wolfgang Hintze" <weh at snafu.de>*Date*: Sat, 15 Oct 2011 06:02:49 -0400 (EDT)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*References*: <j73grj$fvk$1@smc.vnet.net>

Along the lines of Alexei x = A*Exp[I*phi] A*E^(I*phi) (* the next step effectively removes A ; does not work with A < 0 *) FullSimplify[Arg[x], A > 0] Arg[E^(I*phi)] (* now ComplexExpand dos the rest *) y = ComplexExpand[%] ArcTan[Cos[phi], Sin[phi]] Wolfgang ------------ "Ben" <bjgear at googlemail.com> schrieb im Newsbeitrag news:j73grj$fvk$1 at smc.vnet.net... > Would appreciate any help here, endless Googling has not revealed the > answer to me: > > If I define a complex number symbolically, such as x = A Exp[I phi], > why does Arg[x] never return the answer I expect, phi? Using Refine > with the as sumptions phi is real and between 0 and 2 pi, and that A > is greater than 0 doesn't seem to help. All I get is Arg[Exp[I phi]] >