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From: Tom Gederberg <tgederberg@gmail.com>
Newsgroups: comp.graphics.apps.gnuplot
Subject: How to plot data relative to a specific data point
Date: Fri, 10 Feb 2012 09:42:25 -0800 (PST)
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Xref: x330-a1.tempe.blueboxinc.net comp.graphics.apps.gnuplot:934

I know this is probably a stupid question but I have not been able to
find the answer anywhere.

Suppose I have a data file that looks like:

Time    Value1   Value2   Value3

568744.0    -3.2    5.4    8.8
568744.2     9.1    8.1   -3.5
    .               .        .       .
    .               .        .       .
    .               .        .       .
568423.0    5.7     6.1   7.7

I want to plot the data against time, but want time starting at 0, not
568744.0.

I know I can say
plot "data.txt" u ($1 - 568774.0):2 w lines

but is there a way to tell gnuplot to refer to the first time value
(something like $1(0)).  Does this question make sense?