Re: Mathematica 4.2 & Strange Plot results
- To: mathgroup at smc.vnet.net
- Subject: [mg36307] Re: [mg36292] Mathematica 4.2 & Strange Plot results
- From: BobHanlon at aol.com
- Date: Sat, 31 Aug 2002 01:25:49 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
In a message dated 8/30/02 1:44:16 AM, someone at somewhere.com writes: > I would expect that > > Plot[Sin[x]/Sin[x], {x, -2.5, -1.5}] > > would produce a horizontal line at y=1. > > However, on my Windows XP computer it produces a graph where the y value is > less than 1 at several points. Most notibly between x=-1.6 and x=-1.8 > > Is this just an isolated case? Or does it happen to others? If so - why? > $Version 4.1 for Mac OS X (November 5, 2001) p = Plot[Sin[x]/Sin[x],{x,-2.5,-1.5}]; Note that the Ticks on the y-axis are all 1, that is, in trying to find something of interest the adaptive range has zoomed in and is looking at the machine precision representations of 1. (First /@(Ticks /. AbsoluteOptions[p])[[2]])//InputForm Zoom out using the PlotRange Plot[Sin[x]/Sin[x],{x,-2.5,-1.5}, PlotRange->{-0.1,2.1}]; Or as stated in the on-line help for Plot: "You should use Evaluate to evaluate the function to be plotted if this can safely be done before specific numerical values are supplied". Plot[Evaluate[Sin[x]/Sin[x]],{x,-2.5,-1.5}]; Bob Hanlon Chantilly, VA USA