plot and splot are the primary commands of the program. They plot functions and data in many, many ways. plot is used to plot 2-d functions and data, while splot plots 3-d surfaces and data.
Syntax:
plot {ranges} {<function> | {"<datafile>" {using ...}}}
{title} {style} {, <function> {title} {style}...}
splot {ranges} {<function> | {"<datafile>" {index i} {using ...}}}
{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. User-defined functions and variables may also be defined here.
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 with lines,
t**2 with points