Syntax:
plot {ranges} {<function> | {"<datafile>" {datafile-modifiers}}} \ {title} {style} {, {second,} <function> {title} {style}...} splot {ranges} {<function> | {"<datafile>" {datafile-modifiers}}} \ {title} {style} {, <function> {title} {style}...}
where either a <function> or the name of a data file enclosed in quotes is supplied. A function is a mathematical expression, or a pair (plot) or triple (splot) of mathematical expressions in the case of parametric functions. It is also possible to insert user-defined function definitions and variable assignments into the list of plots.
For plot there are two independent sets of axes available: the keywords first and second can be used to change the axes for which the following plots should be scaled. first refers to the axes on the bottom and left; second to those on the top and right. Ranges specified on the plot command apply only to the first set of axes.
The second option has not been implemented for splot.
plot and splot commands can be as simple as
plot sin(x)
and
splot x * y
or as complex as (!)
plot [t=1:10] [-pi:pi*2] tan(t), "data.1" using 2:($3/$4) with lines, \ f(x)=x**p, p=2, second, f(t) with points