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