Re: Possible Bug in ArcTan ?
- To: mathgroup at smc.vnet.net
- Subject: [mg64793] Re: [mg64770] Possible Bug in ArcTan ?
- From: "David Park" <djmp at earthlink.net>
- Date: Thu, 2 Mar 2006 19:28:35 -0500 (EST)
- Sender: owner-wri-mathgroup at wolfram.com
Try the two argument form of ArcTan, ArcTan[x,y]. David Park djmp at earthlink.net http://home.earthlink.net/~djmp/ From: JCDenton [mailto:post4uw at web.de] To: mathgroup at smc.vnet.net Hi Group! I am describing resonant electrical systems with Mathematica. So there is a lot of dealing with complex numbers and functions. One important function is: phi=ArcTan[Im/Re] This function is zero when Im = 0. The problem is, that when I plot this function it shows some strange behaviour near this zero point. It looks somehow, as if the function values are multiplied with -1 or something like that. I also tried to calculate a table an plot this with gnuplot where the stepsize was 0.005. I was the same strange situation. So I am sure it is not the Plot function that is buggy but the ArcTan itself. I also tried the table with step size 0.05 and I get the "right" picture with gnuplot. Is this a known bug? I have not found something about it yet. I realy need this function, since it is a very important operation in complex calculation. Thank you!