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Re: Taking the Arg of a complex number

• To: mathgroup at smc.vnet.net
• Subject: [mg122164] Re: Taking the Arg of a complex number
• From: Ben Gear <bjgear at googlemail.com>
• Date: Mon, 17 Oct 2011 08:10:22 -0400 (EDT)
• Delivered-to: l-mathgroup@mail-archive0.wolfram.com
• References: <j73grj$fvk$1@smc.vnet.net>
• Reply-to: comp.soft-sys.math.mathematica at googlegroups.com

Thanks all for the replies.

Simon's answer seems the most satisfying, interesting that a 'FullSimplify' is required. Refine and Simplify don't cut it (still not 100% how these three differ). I was also being a bit thick about the range of phi I was using.  Getting an answer of ArcTan[Cos[phi], Sin[phi]] also makes sense when the range of phi is not defined.

To those who have suggested that the issue was due to Arg[z] not being evaluated unless z is numeric, as stated in the documentation - this was my first thought, however I think this means that Arg['symbolic variable'] can't be evaluated (which makes sense), rather than Arg['symbolic expression'] can't be evaluated.

Regards,

Ben