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

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From	Karl Ratzsch <mail.kfr@gmx.net>
Newsgroups	comp.graphics.apps.gnuplot
Subject	Re: Samples, isosamples, and how they affect contour lines
Date	Fri, 13 Jul 2018 09:53:02 +0200
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Am 11.07.2018 um 09:02 schrieb nawridlz@gmail.com:

>     set samples 250, 2
>     set isosamples 2, 250
>     set view map
>     splot x**2 + y**2

> To generate correct contour lines, it appears you need to set the first parameter of `samples` and the second parameter of `isosamples` to sufficiently large values. However, setting the second parameter of `samples` and the first parameter of `isosamples` to the smallest possible value does no harm.. This is not exactly intuitive. So how does this work?

Has nothing to do with contours.

"set sample x, y" specifies how many points are generated on each
isoline in the respective direction.

"set isosamp x, y" specifies the number of isolines.

set sample 100,40
set isos 10,4
set view map; splot 1 w p

makes four isolines with 100 points in direction x,
and 10 isolines with 40 points each in direction y.

To not get isolines, but just an even grid, you give the same parameters
to set sample and isosample

set sample 50,20
set isosample 50,20

Actually you can always set one of the isosample parameters to "2", to
get an even grid, you only need the isolines in one direction. And you
can set the sample number in the other direction to "2" also, because
the needed points are already generated by the isolines in the first
direction.

set sample 50,2      # this also makes an even 50:20 matrix
set isosample 2,20

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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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