Plotting Data and Drawing Diagrams

Plotting data

For more sophisticated plotting you may as well try 

xmgr 

or it's descendent 

grace

Drawing diagrams

On machines running Linux, 
to draw figures interactively on X terminal

use the command

xfig 

See the web page on xfig for details.

To draw feynman diagrams in latex language

you can use the package axodraw 

See the web page on axodraw for details.