% gnuplot
You can run [gnuplot](http://www.gnuplot.info/) interactively and it
will open up a window containing your plot. Use the menu bar in the
plot window to export to png or other formats.
Example usage:
$ gnuplot
# Let gnuplot choose the range for you.
gnuplot> plot sin(x)
# Specify the range.
gnuplot> plot [-pi:pi] sin(x)
# Can also specify the range on the y-axis.
gnuplot> plot [-pi:pi] [-0.5:0.5] sin(x)
# Plot multiple functions at once.
gnuplot> plot [-2:2] x, x**2, x**3
# Make a scatter plot from some data (comma- or space-separated).
gnuplot> plot "data.txt"
Links:
* [gnuplot homepage](http://www.gnuplot.info/)
* --- can read this
online.
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* [do a linear fit](https://riptutorial.com/gnuplot/example/27496/fit--basic-linear-interpolation-of-a-dataset)
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