Two Argument ArcTan Function
- To: mathgroup at smc.vnet.net
- Subject: [mg42778] Two Argument ArcTan Function
- From: "David Park" <djmp at earthlink.net>
- Date: Fri, 25 Jul 2003 05:08:36 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
Dear MathGroup,
The two argument function, ArcTan[x,y], is a very nice function and
Mathematica knows how to do a lot with it. But sometimes it is difficult to
bring it into play without just typing it in.
Consider the case of inverting polar coordinates.
eqns = {x == r Cos[t], y == r Sin[t]};
Solve[eqns, {r, t}, {x, y} \[Element] Reals] // Simplify
If we discard the two negative r solutions, we obtain two solutions
involving ArcCos. But couldn't we have a single solution using ArcTan[x,y]?
I'm curious to know if there is a method to get Mathematica to produce that
solution?
David Park
djmp at earthlink.net
http://home.earthlink.net/~djmp/