Re: Very strange behaviour of ArcTan[]
- To: mathgroup at smc.vnet.net
- Subject: [mg102660] Re: Very strange behaviour of ArcTan[]
- From: "David W. Cantrell" <DWCantrell at sigmaxi.net>
- Date: Tue, 18 Aug 2009 06:06:34 -0400 (EDT)
- References: <h6bh4m$6ov$1@smc.vnet.net>
Alexey <lehin.p at gmail.com> wrote: > Hello, > I just have discovered some strange (buggy?) feature of ArcTan[] > function in Mathematica 5.2. Try the following; > > In[72]:= > ArcTan[.5,$MachinePrecision] > ArcTan[.5] > > Out[72]= > 1.53947 > > Out[73]= > 0.463648 > > The expression ArcTan[.5,$MachinePrecision] must (?) give an error No. Look at the documentation for ArcTan. There is a very useful version of ArcTan which takes _two_ arguments. And of course $MachinePrecision merely supplies a numerical value for the second argument. > but > in really gives some strange output without any error messages... What > do you think about this? There's nothing wrong. David