plot {ranges} <function> {title} {style} {, <function> {title} {style}...}
Where <function> is either a mathematical expression or the name of a data file enclosed in quotes. User-defined functions and variables may also be defined here.
Curly braces {,} denote optional items.
A plot command can be as simple as
plot sin(x)
or as complex as (!)
plot [t=1:10] [-pi:pi*2] tan(t),"data.1" with lines,t**2 with points