Re: Weird Plot behavior...

*To*: mathgroup at smc.vnet.net*Subject*: [mg22287] Re: Weird Plot behavior...*From*: "Allan Hayes" <hay at haystack.demon.co.uk>*Date*: Wed, 23 Feb 2000 01:01:20 -0500 (EST)*References*: <88sn7o$ioh@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Doug, You have some pretty steep peaks and valleys which it seem are not being picked up. Increasing PlotPoints helps: Plot[{sf[sf[sf[sf[x]]]], x}, {x, 0, 1}] Plot[{sf[sf[sf[sf[x]]]], x}, {x, 0, 1}, PlotPoints -> 50] Allan --------------------- Allan Hayes Mathematica Training and Consulting Leicester UK www.haystack.demon.co.uk hay at haystack.demon.co.uk Voice: +44 (0)116 271 4198 Fax: +44 (0)870 164 0565 <dougmckee at my-deja.com> wrote in message news:88sn7o$ioh at smc.vnet.net... > I'm getting some strange, seemingly incorrect > graphs from Mathematica 3: > > First I define a simple piecewise continuous > function: > > sf[x_]:=If[x<(1/3),1-3 x,0.5 x - 1/6] > > Then I graph its 4th iterate on [0,1] (along with > y=x): > > Plot[{sf[sf[sf[sf[x]]]],x},{x,0,1}] > > It's missing some information; in particular, the > graph only shows 5 fixed points when I know there > are 7. And when I graph it on [0,2], I _do_ get > all 7 fixed points, and, yes, they're all on > [0,1]: > > Plot[{sf[sf[sf[sf[x]]]],x},{x,0,2}] > > What's going on? Why is the first graph > incorrect, and the second correct? > > Plot[{sf[sf[sf[sf[x]]]],x},{x,0,1},PlotDivision- > >5] > > And here, even though I think I'm setting the > PlotDivision _lower_ than the default (20), I get > the right graph! > > Doug > > > Sent via Deja.com http://www.deja.com/ > Before you buy. >