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} { | {"" {using ...}}}
                     {title} {style} {,  {title} {style}...}

        splot {ranges} { | {"" {index i} {using ...}}}
                     {title} {style} {,  {title} {style}...}

 where either a  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
 Available Subtopic(s):

    data-file           
    errorbars           
    parametric          
    ranges              
    index               
    style               
    title