processing data for gnuplot

[David Fokkema <dfokkema@ileos.nl>]

Hi group,

I was not entirely sure what to put in the subject line...

I did a very simple physics experiment involving two strings, two
weights and one pulley. I'll spare you the details, but by varying one
of the two masses, I measured the angle one of the strings made with the
vertical. I got these results:

# m2      alpha
0       0
10      12
20      23
30      32
15      18
25      27
12      14
22      24
27      29
17      20

where the first column is the mass of the second weight and alpha is the
angle, in which I made an error of ±1 degree. So far, so good.

Now, I want to plot in gnuplot the following: m2 along the x-axis, but
the tangent of alpha with errorbars along the y-axis. So, I have to
process this data somewhat further to obtain a second data file with
three columns: m2, tan alpha-low, tan alpha-high.

Of course, I could use gnumeric or something like that, but I'm
wondering if there are command-line tools out there that could do the
job. Or should I use a scripting language? perl? awk? bc? Efficiency is
not the problem here, ease of use is.

Thanks in advance,

David

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