Axis takes input plot values from standard input. The input values
can be interspersed with commands specifying the various plot options.
Alternatively, plot options can be specified on the command line.
Axis output is in Unix Plot(5) format. This plot ouput can then be
passed through a filter appropriate to the desired plotting device.
There is a filter for putting the plot in an X-window screen. There
are also filters for converting the plot into a graphics print file
for a variety of printers.
The simplest implementation of axis involves simply giving it a list
of x,y pairs as follows:
Axis will draw line segments connecting the three points. It will
choose an appropriate scale for the x and y axis. If you are going to
enter these numbers from the keyboard and want to see the graph on
your screen, simply type
axis | xplot
to filter the axis output through the xplot filter, that puts the
graph on your screen, and then type in the lines as shown. Hit
C-d to signal a keyboard end of file. The plot is then drawn.
Hit q (or C-c in some versions) to signal xplot that you
want to quit.
If your data is in a file called input, then you may use
redirection to get the same result:
axis < input | xplot
To set the x range to the interval [0,1.5], you may use
axis -x 0 1.5 < input | xplot
or you may modify the input data file by adding a line;
#x 0 1.5
Notice that the option is specified with a hyphen on the command line,
and by a separate line with a # in the input file. All of the
axis options work this way. In this course we will put commands in
the input data file most of the time.
The complete documentation for axis and a list of options can be found