Groups > comp.soft-sys.math.mathematica > #2846

Re: FixedPoint[Cos, 1.0]

From	David Reiss <dbreiss@gmail.com>
Newsgroups	comp.soft-sys.math.mathematica
Subject	Re: FixedPoint[Cos, 1.0]
Date	2011-06-01 08:30 +0000
Organization	Steven M. Christensen and Associates, Inc and MathTensor, Inc.
Message-ID	<is4tb3$av4$1@smc.vnet.net> (permalink)
References	<is2kjq$qrm$1@smc.vnet.net>

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Take a look at the comment in the "Possible Issues" section of the
documentation.  This is a "teachable moment" for your students
concerning machine arithmetic and library functions.

Best,
David

On May 31, 7:49 am, J Siehler <jsieh...@gmail.com> wrote:
> My numerical analysis students this past term pointed out to me that
> the command
>
> FixedPoint[Cos, 1.0]
>
> which is the first example in the Information for FixedPoint doesn't
> ever finish running (or, not in any reasonable amount of time).  We
> tried this on serveral versions of Mathematica (6.x, 7.x, and 8.x),
> all on OS X, and got the same nonresult.
>
> It can be forced by specifying something like FixedPoint[Cos, 1.0,
> SameTest -> (Abs[#1 - #2] < 10^-10 &)] or FixedPoint[Cos, 1.0, 40],
> but it seems like that should be unnecessary, and the form given in
> the documentation should work.  Can anybody else confirm this
> behavior?  Am I missing something totally obvious here?

Thread

FixedPoint[Cos, 1.0] J Siehler <jsiehler@gmail.com> - 2011-05-31 11:49 +0000
  Re: FixedPoint[Cos, 1.0] David Reiss <dbreiss@gmail.com> - 2011-06-01 08:30 +0000
  Re: FixedPoint[Cos, 1.0] Szabolcs Horvát <szhorvat@gmail.com> - 2011-06-01 08:30 +0000
  Re: FixedPoint[Cos, 1.0] Szabolcs Horvát <szhorvat@gmail.com> - 2011-06-01 08:30 +0000
  Re: FixedPoint[Cos, 1.0] "Dr. Wolfgang Hintze" <weh@snafu.de> - 2011-06-01 08:32 +0000
  Re: FixedPoint[Cos, 1.0] Erik Max Francis <max@alcyone.com> - 2011-06-01 08:32 +0000

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