Re: Possible Bug in ArcTan ?
- To: mathgroup at smc.vnet.net
- Subject: [mg65315] Re: Possible Bug in ArcTan ?
- From: "EyeCon" <ardasaltoglu at gmail.com>
- Date: Sat, 25 Mar 2006 05:17:57 -0500 (EST)
- References: <email@example.com>
- Sender: owner-wri-mathgroup at wolfram.com
I think you could want to use the function Arg[z], which is guaranteed to give you the correct phase of a complex number. JCDenton wrote: > 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!