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MathGroup Archive 2002

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Re: problems with ContourPlot

  • To: mathgroup at smc.vnet.net
  • Subject: [mg33638] Re: [mg33616] problems with ContourPlot
  • From: Andrzej Kozlowski <andrzej at tuins.ac.jp>
  • Date: Thu, 4 Apr 2002 19:39:57 -0500 (EST)
  • Sender: owner-wri-mathgroup at wolfram.com

Indeed, you seem to have done some "crazy things"! What are all these 
NonCommuativeMulitply's (**) doing in your formula? Are these suppose to 
be * (Times) or ^ (Power)? Assuming the latter the following works fine:

In[6]:=
a =1/2; b = 1/2; c = 1/2; y = 0;

In[7]:=
ContourPlot[Evaluate[(x*(x - a) + y^2 + z^2)/ (Sqrt[(x^2 + y^2 + z^2) ^ 
3]*
           Sqrt[((x - a) ^ 2 + y^2 + z^2) ^ 3]) - ((x - a)*(x - a - b
-c) +
           y^2 + z^2)/ (Sqrt[((x - a) ^ 2 + y^2 + z^2) ^ 3]*
           Sqrt[((x - a - b - c) ^ 2 + y^2 + z^2) ^ 3]) - (x*(x - a -b)
+
           y^2 + z^2)/ (Sqrt[(x^2 + y^2 + z^2) ^ 3]*
           Sqrt[((x - a - b) ^ 2 + y^2 + z^2) ^
               3]) + ((x - a - b)*(x - a - b - c) + y^2 +
           z^2)/(Sqrt[((x - a - b) ^ 2 + y^2 + z^2) ^ 3]*
           Sqrt[((x - a - b - c) ^ 2 + y^2 + z^2) ^ 3])], {x, -1, 1},
{z, 0, 1}, Contours -> {0, 1, 5, 10, 50, 100}, ContourShading -> False]



On Thursday, April 4, 2002, at 08:08  AM, Harald von der 
Osten-Woldenburg wrote:

>
> Hi out there,
>
>
> if I try this:
>
>
> a := 0.5; b := 0.5; c := 0.5; y := 0.0;
>
> ContourPlot[(x*(x - a) + y*y + z*z)/ (Sqrt[(x*x + y*y + z*z) ** 3]*
>           Sqrt[((x - a) ** 2 + y*y + z*z) ** 3]) - ((x - a)*(x - a - b
> -c) +
>           y*y + z*z)/ (Sqrt[((x - a) ** 2 + y*y + z*z) ** 3]*
>           Sqrt[((x - a - b - c) ** 2 + y*y + z*z) ** 3]) - (x*(x - a -b)
> +
>           y*y + z*z)/ (Sqrt[(x*x + y*y + z*z) ** 3]*
>           Sqrt[((x - a - b) ** 2 + y*y + z*z) **
>               3]) + ((x - a - b)*(x - a - b - c) + y*y +
>           z*z)/(Sqrt[((x - a - b) ** 2 + y*y + z*z) ** 3]*
>           Sqrt[((x - a - b - c) ** 2 + y*y + z*z) ** 3]), {x, -1, 1},
> {z, 0, 1}, Contours -> {0, 1, 5, 10, 50, 100}, ContourShading -> False]
>
>
>
>
> I receive the error-messages:
>
>
>
> [ ...Expression... ] is not a machine-size real number at {x, z} =
> {-1.,0.}
>
>
> ContourGraphics::"ctpnt": "The contour is attempting to traverse a cell
> in which some of the points have not evaluated to numbers, and it will
> be dropped."
>
>
> General::"stop": "Further output of (ContourGraphics :: "ctpnt") will be
> suppressed during this calculation."
>
>
>
>
>
> Because I compiled this also with Fortran I know that there are also
> results in the range up to 10^6. Is this too much for ContourPlot? Or
> did I some crazy things.... ?? At (-1,0.) I  cannot find any
> singularity...
>
>
>
> Thank you very much for any small hint.
>
> Harry
>
>
>
>
>
>
>
> --
> Harald von der Osten-Woldenburg
> Geophysical Prospection of Archaeological Sites
> National Heritage Department of Baden-Wuerttemberg
> Silberburgstrasse 193, D-70178 Stuttgart
> Fax Office: +49-(0)711-1694-707
> http://www.lb.netic.de/hvdosten : Geomagnetics, Geoelectrics, Radar, EMI
>
>
>
>
>
>
>
Andrzej Kozlowski
Toyama International University
JAPAN
http://platon.c.u-tokyo.ac.jp/andrzej/



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