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Newsgroups: comp.graphics.apps.gnuplot
Date: Tue, 24 Oct 2017 15:13:11 +0200
From: Jean-Pierre Coulon <coulon@cacas.pam.obs-nice.fr>
Subject: Re: can I fit two columns when I use timefmt
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On Tue, 24 Oct 2017, Jörg Buchholz wrote:

> On 24.10.2017 13:30, Jean-Pierre Coulon wrote:
>> I have a datafile with lines like 171023_15h11m59s150 <value2> <value3>.
>> I know how to plot columns 2 and 3 using set xdata time; set timefmt
>> "%y%m%d_%Hh%Mm%Ss"
>
> You plot value2 and value3 by using value1 (your time data) as x value?
>
> plot 'datafile' u 1:2, '' u 1:3

This already works fine.

>> My model is a = .028; b=.04; model(x) = a*x + b. When I say
>> fit modele(x) "mystuff.txt" using 2:3 via a, b I obtain: No data to fit
>
> Here you use value2 as xdata and they don't have a timeformat.
>
>> What is the right way to do?
>
> Before fitting 2:3 unset xdata time by using
>
> set xdata

Thanks. It works if I also say unset xrange. In this case I also have a first 
column in simple integers and the 2nd column is in time format. I was plotting 
with using 2:<other column>. Does Gnuplot use this 1srt column for the fit 
if I say fit using <two other columns> ?

Jean-Pierre Coulon