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Re: implcit plot with undefined expression

  • To: mathgroup at smc.vnet.net
  • Subject: [mg18830] Re: implcit plot with undefined expression
  • From: "Dale Horton" <daleh at wolfram.com>
  • Date: Thu, 22 Jul 1999 08:19:40 -0400
  • Organization: Wolfram Research, Inc.
  • References: <7n13kb$bf2@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

You can use Solve to create explicit equations and Plot the results.

In[1]:=
eqn = Sqrt[2*Sqrt[2X^2 - Y^2] - 2*Y + X^2] == 0

Out[1]=
Sqrt[X^2 - 2*Y + 2*Sqrt[2*X^2 - Y^2]] == 0

In[2]:=
cont = Y /. Solve[eqn, Y]

Out[2]=
{1/4*(X^2 - Sqrt[16*X^2 - X^4]),
  1/4*(X^2 + Sqrt[16*X^2 - X^4])}

In[3]:=
Plot[Evaluate[cont], {X, -1, 1}]

-Dale

<zoominzero at hotmail.com> wrote in message news:7n13kb$bf2 at smc.vnet.net...
> Hi,
> I've spent 4 days to try to use ImplicitPlot on an equation, without
> success:
> 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
>
>
> Sent via Deja.com http://www.deja.com/
> Share what you know. Learn what you don't.
>




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