Among the scores of graphic packages available, gnuplot stands out for its power and ease of use. Go to X and type gnuplot, and have two sample data files ready: 2D-data.dat (two data per line), and 3D-data.dat (three data per line).
Examples of 2-D graphs:
gnuplot> set title "my first graph" gnuplot> plot '2D-data.dat' gnuplot> plot '2D-data.dat' with linespoints gnuplot> plot '2D-data.dat', sin(x) gnuplot> plot [-5:10] '2D-data.dat'
Example of 3-D graphs (each `row' of X values is followed by a blank line):
gnuplot> set parametric ; set hidden3d ; set contour gnuplot> splot '3D-data.dat' using 1:2:3 with linespoints
A single-column datafile (e.g., a time series) can also be plotted as a 2-D graph:
gnuplot> plot [-5:15] '2D-data-1col.dat' with linespoints
or as a 3-D graph (blank lines in the datafile, as above):
gnuplot> set noparametric ; set hidden3d gnuplot> splot '3D-data-1col.dat' using 1 with linespoints
To print a graph: if the command to print on your Postscript printer is lpr -Pps file.ps, issue:
gnuplot> set term post gnuplot> set out '| lpr -Pps' gnuplot> replot
then type set term x11 to restore. Don't get confused---the last print will come out only when you quit gnuplot.
For more info, type help or see the examples in directory /usr/lib/gnuplot/demos/, if you have it.