MathGroup Archive: August 2009 [00472]

[Date Index] [Thread Index] [Author Index]

Very strange behaviour of ArcTan[]

To: mathgroup at smc.vnet.net
Subject: [mg102656] Very strange behaviour of ArcTan[]
From: Alexey <lehin.p at gmail.com>
Date: Mon, 17 Aug 2009 08:06:56 -0400 (EDT)

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?

Follow-Ups:
- Re: Very strange behaviour of ArcTan[]
  - From: "Tony Harker" <a.harker@ucl.ac.uk>
- Re: Very strange behaviour of ArcTan[]
  - From: Adriano Pascoletti <adriano.pascoletti@dimi.uniud.it>
- Re: Very strange behaviour of ArcTan[]
  - From: DrMajorBob <btreat1@austin.rr.com>
- Re: Very strange behaviour of ArcTan[]
  - From: "Curtis F. Osterhoudt" <cfo@lanl.gov>
- Re: Very strange behaviour of ArcTan[]
  - From: Louis Talman <talmanl@gmail.com>

Prev by Date: Re: Standard deviations and Confidence intervals with respect to

Next by Date: "Mathematica could not establish a connection to the kernel"

Previous by thread: Re: Standard deviations and Confidence intervals with respect to

Next by thread: Re: Very strange behaviour of ArcTan[]