Re: Strange RegionPlot
- To: mathgroup at smc.vnet.net
- Subject: [mg81569] Re: Strange RegionPlot
- From: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>
- Date: Fri, 28 Sep 2007 02:06:44 -0400 (EDT)
- Organization: The Open University, Milton Keynes, UK
- References: <fddfh1$a67$1@smc.vnet.net>
Bruce Colletti wrote:
> Re 6.0.1 under Windows XP.
>
> The region returned by:
>
> RegionPlot[x + y < 4 && x - y > 3, {x, -20, 25}, {y, -20, 10}]
>
> should be triangular. Yet the apex is a short line segment and not a vertex.
>
> What creates this segment, and what must one do to get the vertex? Thankx.
Hi Bruce,
A good guess is that the adaptive sampling scheme is set too low for
this graphic. A value of 4 or 5 for the option *MaxRecursion* should
yield the correct result.
GraphicsColumn[
RegionPlot[x + y < 4 && x - y > 3, {x, -20, 25}, {y, -20, 10},
ImageSize -> 400, MaxRecursion -> #,
PlotLabel -> StringJoin["MaxRecursion -> ", ToString@#]] & /@
Range[0, 10]]
(Or see http://homepages.nyu.edu/~jmg336/mathematica/StrangeRegionPlot.pdf)
Regards,
--
Jean-Marc