Re: FixedPoint[Cos, 1.0]

*To*: mathgroup at smc.vnet.net*Subject*: [mg119362] Re: FixedPoint[Cos, 1.0]*From*: David Reiss <dbreiss at gmail.com>*Date*: Wed, 1 Jun 2011 04:30:32 -0400 (EDT)*References*: <is2kjq$qrm$1@smc.vnet.net>

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... at 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?