Groups > comp.soft-sys.math.mathematica > #2136

Re: Bug in ListContourPlot?

From	Peter Pein <petsie@dordos.net>
Newsgroups	comp.soft-sys.math.mathematica
Subject	Re: Bug in ListContourPlot?
Date	2011-05-06 11:23 +0000
Organization	Steven M. Christensen and Associates, Inc and MathTensor, Inc.
Message-ID	<iq0loe$2p4$1@smc.vnet.net> (permalink)
References	<ipbg07$agf$1@smc.vnet.net>

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Am 28.04.2011 12:36, schrieb Barak Shoshany:
> Please copy and paste this into a Mathematica notebook:
>
> ListContourPlot[{{0.42256875000000005`, 3091.38125`,
>     8.271213205043878`}, {0.42256875000000005`, 3092.00625`,
>     6.266039117378199`}, {0.4263187500000001`, 3091.38125`,
>     5.613752062730342`}, {0.4263187500000001`,
>     3092.00625`, -5.684341886080802`*^-14}, {0.4263187500000001`,
>     3092.63125`, 5.599651386371079`}, {0.43006875000000006`,
>     3092.00625`, 6.059667975471868`}}]
>
> When I execute this code on my computer (Mathematica v8.0.1, Windows 7
> x64), the Mathematica kernel hangs. Does this happen to anyone else as
> well?
>
> Barak
>
Hi!

Just a (late) proposal for cases like this:

Try to rationalize the values, but _not_ to full precision:

ListContourPlot[
  tbl = Rationalize[intbl={{0.42256875000000005`, 3091.38125`,
      8.271213205043878`}, {0.42256875000000005`, 3092.00625`,
      6.266039117378199`}, {0.4263187500000001`, 3091.38125`,
      5.613752062730342`}, {0.4263187500000001`,
      3092.00625`, -5.684341886080802`*^-14}, {0.4263187500000001`,
      3092.63125`, 5.599651386371079`}, {0.43006875000000006`,
      3092.00625`, 6.059667975471868`}}, 10^-$MachinePrecision]]

works great on Version 8.01/Win7-64 and reveals a set of levels of 
contours like concentric squares.
  But be sure, not to use "Rationalize[....,0]"!


As a measure for the error,

tbl - intbl // Flatten // Norm

--> 8.98526*10^-16

seems small enough to me.

Cheers,
Peter

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Thread

Bug in ListContourPlot? Barak Shoshany <baraksh@gmail.com> - 2011-04-28 10:36 +0000
  Re: Bug in ListContourPlot? Ulf-Dietrich Braumann <braumann@uni-leipzig.de> - 2011-05-01 10:22 +0000
    Re: Bug in ListContourPlot? Barak Shoshany <baraksh@gmail.com> - 2011-05-02 10:52 +0000
  Re: Bug in ListContourPlot? Yves Klett <yves.klett@googlemail.com> - 2011-05-02 10:53 +0000
  Re: Bug in ListContourPlot? Peter Pein <petsie@dordos.net> - 2011-05-06 11:23 +0000

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