GNUPlot Manual

46 gnuplot 4.0 28 PLOT
28.4 Parametric
When in parametric mode (set parametric) mathematical expressions must be given in pairs for plot
and in triplets for splot.
Examples:
plot sin(t),t**2
splot cos(u)*cos(v),cos(u)*sin(v),sin(u)
Data files are plotted as before, except any preceding parametric function must be fully specified before
a data file is given as a plot. In other words, the x parametric function (sin(t) above) and the y
parametric function (t**2 above) must not be interrupted with any modifiers or data functions; doing
so will generate a syntax error stating that the parametric function is not fully specified.
Other modifiers, such as with and title, may be specified only after the parametric function has been
completed:
See also
plot sin(t),t**2 title ’Parametric example’ with linespoints
Parametric Mode Demos.
28.5 Ranges
The optional ranges specify the region of the graph that will be displayed.
Syntax:
[{=}{{}:{}}]
[{{}:{}}]
The first form applies to the independent variable (xrange or trange, if in parametric mode). The second
form applies to the dependent variable yrange (and xrange, too, if in parametric mode).
is a new name for the independent variable. (The defaults may be changed with set dummy.)
The optional and terms can be constant expressions or *.
In non-parametric mode, the order in which ranges must be given is xrange and yrange.
In parametric mode, the order for the plot command is trange, xrange, and yrange. The following
plot command shows setting the trange to [-pi:pi], the xrange to [-1.3:1.3] and the yrange to [-1:1]
for the duration of the graph:
plot [-pi:pi] [-1.3:1.3] [-1:1] sin(t),t**2
Note that the x2range and y2range cannot be specified here — set x2range and set y2range must be
used.
Ranges are interpreted in the order listed above for the appropriate mode. Once all those needed are
specified, no further ones must be listed, but unneeded ones cannot be skipped — use an empty range
[] as a placeholder.
* can be used to allow autoscaling of either of min and max. See also set autoscale (p. 54).
Ranges specified on the plot or splot command line affect only that graph; use the set xrange, set
yrange, etc., commands to change the default ranges for future graphs.
With time data, you must provide the range (in the same manner as the time appears in the datafile)
within quotes. gnuplot uses the timefmt string to read the value — see set timefmt (p. 143).
Examples:
This uses the current ranges:
plot cos(x)
This sets the x range only:
plot [-10:30] sin(pi*x)/(pi*x)