Redefine Arg to return a value from 0 to 2 pi
- To: mathgroup at smc.vnet.net
- Subject: [mg80408] Redefine Arg to return a value from 0 to 2 pi
- From: chuck009 <dmilioto at comcast.com>
- Date: Tue, 21 Aug 2007 05:09:55 -0400 (EDT)
I'm trying to redefine Arg to return a value from 0 to 2 pi. However when I do so and then try and plot Arg[z], Mathematica seems to still use the old definition. Can anybody help me? This is my code:
(* redefine Arg to return a value from 0 to 2 pi *)
Unprotect[Arg]
Arg[z_] := Module[{z0 = z}, If[Im[z0] < 0,
ArcTan[Re[z0], Im[z0]] + 2*Pi, ArcTan[Re[z0],
Im[z0]]]];
Protect[Arg]
(* check new definition -- this is correct *)
ListPlot[Table[{t, Arg[2*Exp[I*t]]}, {t, 0, 4*Pi, 0.1}]]
(* try and plot new definition of Arg -- Plot used the old definition (-pi to pi) *)
Plot[Arg[2*Exp[I*t]], {t, 0, 4*Pi}]
(* resore old definition of Arg *)
Unprotect[Arg]
Arg[z_] =.
Protect[Arg]