Services & Resources / Wolfram Forums
-----
 /
MathGroup Archive
2006
*January
*February
*March
*April
*May
*June
*July
*August
*September
*October
*November
*December
*Archive Index
*Ask about this page
*Print this page
*Give us feedback
*Sign up for the Wolfram Insider

MathGroup Archive 2006

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: ContourPlot and finite approximation to level sets

  • To: mathgroup at smc.vnet.net
  • Subject: [mg68638] Re: ContourPlot and finite approximation to level sets
  • From: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>
  • Date: Mon, 14 Aug 2006 06:44:09 -0400 (EDT)
  • Organization: The Open University, Milton Keynes, UK
  • References: <ebmu7p$6q9$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

dkjk at bigpond.net.au wrote:
> Hi all,
> 
> Given a real-valued function f(x,y) over {(x,y) | xmin < x < xmax, ymin
> < y < ymax}, ContourPlot can be used to generate the graph of the level
> set { (x,y) | f(x,y) = c } using
> 
> ContourPlot[f[x,y],{x,xmin,xmax},{y,ymin,ymax},Contours->{c},ContourShading->False].
> 
> Is there any way to access the coordinates used by Mathematica to paint
> the contour line of height c? If not, can anyone suggest an algorithm,
> such as the one used by Mathematica, to finitely approximate a level
> set?

Hi James,

The array of points (by default 25x25 points)is the first element of the 
SurfaceGraphics object return by ContourPlot. For example,

cp = ContourPlot[Sin[x*y], {x, -1, 1}, {y, -1, 1}, Contours -> {0.5}, 
ContourShading -> False];
FullForm[cp]
Dimensions[cp[[1]]]

Best regards,
Jean-Marc


  • Prev by Date: Re: using answer form reduce
  • Next by Date: Re: MemberQ
  • Previous by thread: Re: ContourPlot and finite approximation to level sets
  • Next by thread: RE: ContourPlot and finite approximation to level sets