This is the source to Pdplot, an X11 graphing tool for ASCII data
streams.  Pdplot duplicates the command set of the Agilent/HP graphing
package Autoplot written by Bob Jewett.  It is written in C and Xlib and
is released under GPL v2.  The author is Rick Walker
(walker@omnisterra.com).  The Pdplot git repository is at
http://www.omnisterra.com/git. 

To build Pdplot, do:

    make depend
    make
    sudo make install

The binary (pdplot) and launching script (pd) will be put in
/usr/local/bin/ and the font files with go to /usr/local/lib/pdplot

Pdplot uses a fifo file for input.  The location for the fifo is
specified in the pd script and defaults to /var/spool/sockets/pdplot/. 
Pd will attempt to create this directory the first time it runs, but if
there is a permission problem, you may have to make this directory by
hand as superuser. 

See the pd.1 man page for details (man pd). 

Here's a simple plot to try:

----------- cut here -------------
title XYZ stock price
xscale 1 year
yscale 1 price
1999 50
2000 52
2001 55
2004 60
----------- cut here -------------

Save as stock.pd and run "pd stock.pd" or "pd < stock.pd"

Here's a little awk script to plot a sinewave:

----------- cut here -------------
awk '
   BEGIN {
     print "sine wave"
     print "xscale 1 value"
     print "yscale 1 time"
     for (i=0; i<=3; i+=.02) {
        print i, sin(2*3.14159*i)
     }
   }
'
----------- cut here -------------

Save as sine.awk, do "chmod -x sine.awk", and then run "sine.awk | pd". 

If you make the obvious modification to sine.awk to create cosine.awk,
then you can add the cosine plot to the *existing* graph by doing
"cosine.awk | pd -n".   The -n option adds the new data to the existing
data, rescales the axes and updates the graph.
	
--
Rick Walker