Groups > comp.graphics.apps.gnuplot > #4007

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	2018-07-12 17:18 +0200
Organization	solani.org
Message-ID	<pi7rfv$22d$1@solani.org> (permalink)
References	<884eb2ab-a118-41a9-aaa1-bfcdd71f0d0e@googlegroups.com> <pi4igh$v3p$1@solani.org> <31e8c304-ae02-4814-b3f3-48c06a77dded@googlegroups.com> <pi6r9e$cjn$1@solani.org> <5187f490-08b0-4d98-acea-61f0ff158f3f@googlegroups.com>

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Am 12.07.2018 um 08:50 schrieb nawridlz@gmail.com:
> By y-grid you mean the plane z = 80?
> 
no, the sampling distance between points in direction y.

   set sample 6	
   set isosample 500

gives a grid with 6 points in direction x, times 500 in direction y.
That's the grid you see with

   set view map
   splot $surface

How should the contour routine know what the z values at x=0 are when
there is nothing to interpolate between?

Actually your contour is terrible between [-10:-6] and [6:10] too. It
looks nice and round, but is a very sketchy interpolation, much worse
even in [-6:-2] and [2:6]

  reset
  set samp 100
  set isos 100
  set table $surf200 # this is a well-gridded plot
  splot x**2+y**2

  set samp 6
  set isos 500
  set table $surface # this isn't
  rep
  unset table

  set view map
  set cntrparam levels discrete 20, 40, 60, 80
  set contour
  unset surface   # comment out to see the grid
  splot $surf200 w l title "200x200 grid", \
        $surface w p ps .5 pt 1 title "6x500 grid"

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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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