To start exploring *gnuplot*, try the following commands:

plot cos(x) plot [-pi:pi] sin(x**2),cos(exp(x)) splot [-3:3] [-3:3] x**2*yThe first

Here are explanations of the above commands. The `plot` command
tells *gnuplot* that you want to create a two-dimensional plot. In the first
example, the range of *x* is not specified, so *gnuplot* use its default
range of (-10,10). In the second example, the phrase `[-pi:pi]`
following `plot` tells *gnuplot* to produce the plot with *x* in the
range . There are two functions specified, separated by a
comma. This tells *gnuplot* to plot both functions on the same plot.
Note that on a color screen, *gnuplot* uses different colors for the
functions. On a monochrome display, the functions are plotted with
different line styles. The third command tells *gnuplot* to create a
three-dimensional plot (well, actually a two-dimensional projection
of a three-dimensional plot, but you know that). The two
pairs of brackets following `splot` set the range of the *x*-axis
(first set of brackets) and the range of *y*-axis (second set of
brackets). Note that the ranges are optional in both `plot` and
`splot`. If ranges are not specified, *gnuplot* uses the ranges
previously set. The ranges of *y*-axis in `plot` and the *z*-axis
in `splot` are autoscaled by default, if not specified.

If you want to specify the *y*-range but not the *x*-range, put in both
sets of brackets but leave the first set empty, like

plot [] [0:2] 1/(1+x**2)The same trick works with

The command `set` is used to control many options
available in *gnuplot* (you have already seen `set terminal`). Many
of the options control the appearance of the plot. In the previous
examples, you saw that the ranges of the axes can be specified in the
plotting command. The ranges can also be set before plotting, with the
commands `set xrange`, `set yrange`, and `set zrange`. For
example:

set xrange [-.3:3.5] set yrange [:pi**2] set zrange [exp(3.66)/sin(1.2*pi):]Note that you can omit either the upper or lower limits. The limits can be either numbers, pre-defined constants , or expressions as complicated as in the third example.

The difference between setting the ranges with `plot` (or `splot`)
and with `set xrange` (or `yrange` or `zrange`) is that in
the former case the ranges apply only to that single plot, whereas in the
latter case they apply to all subsequent plots - until the ranges are
reset, of course. (If the ranges are set both ways, the ones on the
`plot` command will be used.) This is the case for all `set`
commands.

If you have set a range and want to return to *gnuplot*'s automatic range
selection, the command is `set autoscale` *axis* , where
*axis* is some combination of *x*, *y*, and *z* and, if you
omit it, all axes will be autoscaled.

You can also add axis labels and a title to the plot by the commands `
set xlabel`, `set ylabel`, `set zlabel`, and `set title`.
For example:

set xlabel 'x' set ylabel "Power Function" set zlabel 'Time (sec)' set title 'Some Examples' replotNote that both single quote and double quote are acceptable (but they must match). The

You can also add another curve to the previous plot. Try

plot [-2*p1:2*pi] sin(x) replot tan(x)Note that the

Tue Jul 16 23:20:34 CDT 1996