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Re: Contour levels

  • To: mathgroup at smc.vnet.net
  • Subject: [mg83793] Re: Contour levels
  • From: "Kevin J. McCann" <Kevin.McCann at umbc.edu>
  • Date: Sat, 1 Dec 2007 05:33:19 -0500 (EST)
  • Organization: University System of Maryland
  • References: <fiopjh$9gd$1@smc.vnet.net>

Couldn't you just evaluate your function for the first point in each 
contour?

Kevin

sigmundv at gmail.com wrote:
> A few days ago a question was posted on how to extract the coordinates
> defining each of the contours returned by ContourPlot[]. Then I would
> like to ask if there is any way to also get the level they belong to?
> Let me illustrate the question by an example:
> 
> If I plot the contours (or level curves) of the scalar function f(x,y)
> = x^2 + y^2 by using
> 
> cplot = ContourPlot[x^2+y^2,{x,-1,1},{y,-1,1}]
> 
> in Mathematica 6.0, I get a few circles. The points defining these
> circles are extracted as follows:
> 
> Cases[First[cplot] // Normal, Line[pts_] -> pts, Infinity];
> 
> This returns a few lists, each containing a selection of points on a
> circle. Then my question is, if there is any way I can get the level
> to which each of these lists belong. That is, can I ask Mathematica
> which list of points belongs to f(x,y) = 0.4, for example, or, which
> level does a given list of points belong to?
> 
> Kind regards,
> Sigmund Vestergaard
> 

-- 

Kevin J. McCann
Research Associate Professor
JCET/Physics
Physics Building
University of Maryland, Baltimore County
1000 Hilltop Circle
Baltimore, MD 21250


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