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Re: implcit plot with undefined expression

  • To: mathgroup at
  • Subject: [mg18817] Re: [mg18780] implcit plot with undefined expression
  • From: "Richard Finley" <rfinley at>
  • Date: Thu, 22 Jul 1999 08:19:32 -0400
  • Sender: owner-wri-mathgroup at

I didn't have any problem using ImplicitPlot on this equation...note that 
you can get rid of the outer square root since if it is zero the argument 
must be zero also.

In[1]:= eq = 2*Sqrt[2*x^2 - y^2] - 2*y + x^2 == 0 ;
In[2]:= <<Graphics`ImplicitPlot`
In[3]:= ImplicitPlot[eq, {x,-Sqrt[2]*2, Sqrt[2]*2}]

and the result is a curve symmetrical about the origin as you would expect 
since the equation only involves terms in x^2.   Since you didn't give us 
the "real" equation you are interested in, it is hard to know if there is 
some other problem affecting your output.  Regards, RF

>>> <mathgroup at> 07/19/99 11:33PM >>>
I've spent 4 days to try to use ImplicitPlot on an equation, without
The Equation I try to plot has 2 nested square roots, ans 2 variables :
something like Sqrt[2*Sqrt[2X^2 -Y^2] - 2*Y +X^2]==0
(it's not exactly this one: it's  just to give you an idea )

Of course this equation is not defined everywhere, and the domain where
it's defined is complex. When i try to "ImplicitPlot" this equation,
i've an answer :
"The contour is attempting to traverse a cell in which some of the
points have not evaluated to numbers, and it will be dropped"
followed by
"Further output of ContourGraphics::"ctpnt" will be suppressed during
this calculation."

So i don't have any answers ( and there are answers of course :)

Is there some options or another solution to draw this implicit equation

Thanks by advance

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