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Re: ImplicitPlot problem

  • To: mathgroup at smc.vnet.net
  • Subject: [mg68171] Re: ImplicitPlot problem
  • From: "Jens-Peer Kuska" <kuska at informatik.uni-leipzig.de>
  • Date: Thu, 27 Jul 2006 05:29:49 -0400 (EDT)
  • Organization: Uni Leipzig
  • References: <ea72a7$k44$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Hi,

the problem is, that Mathematica assume the 
function is continuous.
Because x/y change it sign from y==0-eps to 
y==0+eps and it
asssume that there must be a zero between the sign 
changes.
But the Numerator will not contribute an zero and
ImplicitPlot[Denominator[x/y] == 0, {x, -1, 1}, 
{y, -1, 1}]

will do it.

Regards

  Jens


"Antonios Papazoglou" 
<antonios.papazoglou at epfl.ch> schrieb im 
Newsbeitrag news:ea72a7$k44$1 at smc.vnet.net...
|
|
| Hello,
|
| I'm using ImplicitPlot to plot the line of zeros 
of a complicated function
| f(x,y) on the (x,y) plane. However, not only the 
line of zeros is ploted,
| but also the line where the function f diverges.
|
| Simple example: take f(x,y)=x/y
| Then ImplicitPlot plots a cross, although the 
zeros are only the line x=0.
|
| This is probably due to a problem of the 
underlying ContourPlot function
| that is used implicitly.
|
| Is there a way around this problem?
|
| Thanks, Antonios
| 



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