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MathGroup Archive 2002

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Re: problems with ContourPlot

  • To: mathgroup at smc.vnet.net
  • Subject: [mg33635] Re: [mg33616] problems with ContourPlot
  • From: BobHanlon at aol.com
  • Date: Thu, 4 Apr 2002 19:39:53 -0500 (EST)
  • Sender: owner-wri-mathgroup at wolfram.com

In a message dated 4/3/02 8:14:53 PM, hvdosten at lb.netic.de writes:

>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...
>

replace all uses of ** with ^

** is NonCommutativeMultiply

^ is Power


Bob Hanlon
Chantilly, VA  USA


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