Groups > comp.graphics.apps.gnuplot > #4011

Re: Samples, isosamples, and how they affect contour lines

From	Karl Ratzsch <mail.kfr@gmx.net>
Newsgroups	comp.graphics.apps.gnuplot
Subject	Re: Samples, isosamples, and how they affect contour lines
Date	2018-07-13 12:39 +0200
Organization	solani.org
Message-ID	<pi9vho$bpp$1@solani.org> (permalink)
References	(2 earlier) <31e8c304-ae02-4814-b3f3-48c06a77dded@googlegroups.com> <pi6r9e$cjn$1@solani.org> <5187f490-08b0-4d98-acea-61f0ff158f3f@googlegroups.com> <pi7rfv$22d$1@solani.org> <62c2956e-101c-4c7d-8fc1-313f5670c3b5@googlegroups.com>

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Am 13.07.2018 um 09:22 schrieb nawridlz@gmail.com:
> Can we go through a simple example? Consider once again the following case:
> 
>     set samples 6
>     set isosamples 21
>     set table $surface
>     splot x ** 2 + y ** 2
>     unset table
>     set contour
>     set cntrparam levels discrete 80
>     set view map
>     splot $surface
> 
> Now, you wrote:
> 
>> gnuplot takes the grid values in x-direction, and adds an interpolated
>> contour point wherever the connection between these two points crosses
>> the y-grid.

> If I understand correctly, we consider two grid points consecutive in x-direction, for example (-6, -8) and (-2, -8). Now, we add a contour point between them, according to the plot at (-3.5, -8). Why exactly at (-3.5, -8)?

That is where a line parallel to the x-axis at y=-8 and z=80 goes
through that the badly sampled surface of z = x^2 + y2. At least that is
how I understand the contour generation algorithm.

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Thread

Samples, isosamples, and how they affect contour lines nawridlz@gmail.com - 2018-07-11 00:02 -0700
  Re: Samples, isosamples, and how they affect contour lines Karl Ratzsch <mail.kfr@gmx.net> - 2018-07-11 11:26 +0200
    Re: Samples, isosamples, and how they affect contour lines nawridlz@gmail.com - 2018-07-11 22:39 -0700
      Re: Samples, isosamples, and how they affect contour lines Karl Ratzsch <mail.kfr@gmx.net> - 2018-07-12 08:08 +0200
        Re: Samples, isosamples, and how they affect contour lines nawridlz@gmail.com - 2018-07-11 23:50 -0700
          Re: Samples, isosamples, and how they affect contour lines Karl Ratzsch <mail.kfr@gmx.net> - 2018-07-12 17:18 +0200
            Re: Samples, isosamples, and how they affect contour lines nawridlz@gmail.com - 2018-07-13 00:22 -0700
              Re: Samples, isosamples, and how they affect contour lines Karl Ratzsch <mail.kfr@gmx.net> - 2018-07-13 12:39 +0200
  Re: Samples, isosamples, and how they affect contour lines Karl Ratzsch <mail.kfr@gmx.net> - 2018-07-13 09:53 +0200

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