             How to plot large data sets

Let me describe my experirince with plotting large data sets.

Given two ascii data files (each 9 MB large),
each consisting of 10^6 decimal numbers - observations along x and y axis,
you can use xpplot (ftp.funet.fi:/pub/graphics/packages/xpplot/xpplot.tar.gz)
to see the data and to make a PostScript plot (20 MB).
This takes less than 5 minutes on a HP 712 workstation with 32 MB RAM.

Then you can use Ghostscript with ljet4 driver to convert the PostScript file 
to the PCL5 file 
(0.8 to 2.6 MB, depends on the percentage of the used plotting area,
0.8 MB for 12 cm x 12 cm picture, 2.6 MB for full A4)
suitable for a HP LJ 4 or 5 printer with 600 dpi resolution.
This takes less than 6 minutes on a HP 712 workstation with 32 MB RAM.

It is important to note that even a HP LJ 5L printer with only 1 MB of RAM
prints the 2.6 MB PCL5 file O.K.

Good luck

Pavel POKORNY                   Department of Mathematics
phone: +42 2 24 35 30 96        Prague Institute of Chemical Technology
fax:   +42 2 31 13 629          Technicka 5
 or    +42 2 24 31 10 82        166 28 Prague
e-mail: Pavel.Pokorny@vscht.cz  Czech Republic

time rand 1000000 > x      #  55.2 s   9   MB
time tail -n+2 x > y       #   8.1 s   9   MB
time p -b -l0 -fh x y      # 276.6 s  20   MB
time gslj44 h              # 362.6 s   0.8 MB
time lp -or h.lj4          #   0.1 s
                           #--------
                           # 703.2 s

