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Re: Very strange behaviour of ArcTan[]

  • To: mathgroup at smc.vnet.net
  • Subject: [mg102671] Re: [mg102656] Very strange behaviour of ArcTan[]
  • From: "Curtis F. Osterhoudt" <cfo at lanl.gov>
  • Date: Tue, 18 Aug 2009 06:08:37 -0400 (EDT)
  • References: <200908171206.IAA06945@smc.vnet.net>
  • Reply-to: cfo at lanl.gov

You've discovered the two-argument form of ArcTan; that is, it's returning
ArcTan[15.9546/0.5]. I suspect you want to feed a precision to Mathematica
in another way ...



> 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 but
> in really gives some strange output without any error messages... What
> do you think about this?
>
>



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