Re: AngularFormat again

• To: mathgroup at smc.vnet.net
• Subject: [mg21215] Re: AngularFormat again
• From: phbrf at t-online.de (Peter Breitfeld)
• Date: Fri, 17 Dec 1999 01:29:14 -0500 (EST)
• References: <831sfd\$fit@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```Alan W.Hopper <awhopper at hermes.net.au> schrieb:
> Hi everybody,
[*** snipp ***]
> Lastly, I wonder if anyone has a comment to make on the program below
> which shows the difficulty in getting a 'correct' angle from coordinates
> in all the 4 quadrants of the real Cartesian plane.  Should there
> be a built-in option to always get a positive angle result in Mathematica?
>
>
> In[27]:=
> 		N[
> 			a1 = ArcTan[y/x]/ Degree;
> 			a2 = ArcTan[x,y]/ Degree;
> 			a3 = a2;
> 			If[a3 < 0, a3 = a3 + 360];
> 			quots = Tan[a3 Degree];
> 			{a1,a2,a3,quots},12]]
>
[*** snipp ***]
>
> I know that a2 is valid by Mathematica's Tan and ArcTan definitions,
>
> (Help Browser - ArcTan[x, y] gives the arc tangent of y/x,
> taking into account which quadrant the point a is in.)
>
> But I personally prefer the a3 result.

The easiest (?) would be

a3= Mod[Tan[x,y],2Pi]/Degree

Gruss Peter
--
=--=--=--=--=--=--=--=--=--=--=--=--=  http://home.t-online.de/home/phbrf  =--=
=--= Peter Breitfeld, Saulgau, Germany        PGP public key: 08548045  =--=--=

```

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