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From: Karl Ratzsch <mail.kfr@gmx.net>
Newsgroups: comp.graphics.apps.gnuplot
Subject: Re: dgrid3d and logscale xy with gridded data
Date: Thu, 8 Nov 2018 11:17:06 +0100
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Am 08.11.2018 um 09:22 schrieb rowlesmr@gmail.com:
> Hi all
> 
> I have some grid data which I would like to plot as a surface. I want the xy axes to be logscale. 
> 
> I would like to interpolate the data onto a finer grid so that I can have nice contours and that the colour gradient looks nicer.
> 
> As far as I can tell, it looks like dgrid3d does the gridding in linear space, and then logscale does the axis conversion.
> 
> How can I grid the data in log space?
> 

I would say don't logscale the axes, but plot the logarithmised (is that
an adjective?) data:

	reset
	set dgrid3d splines 60,60
	splot "dat.txt" using (log10($1)):(log10($2)):3 w l

If you want your regular (nonlog) axis ticlabels back, you can manually
relabel them, or perhaps someone else can help with getting the linked

	set link x2 via 10**x inverse log10(x)
	set link y2 via 10**y inverse log10(y)

x2 and y2 axes to show. Not sure how/if that works.

  Karl