Plotting large numbers of positions

PONGO can store $5000$ positions at any time. This can very occasionally cause problems for specific types of use. One way in which you can actually plot more positions than this, is by reading in the data in chunks (of 5000 points) and plotting these. The following ICL procedure shows one way in which you might do this:

proc superplot file, x1, x2, y1, y2, n
  begplot xwindows xmin=(x1) xmax=(x2) ymin=(y1) ymax=(y2)
  limits (x1) (x2) (y1) (y2)
  boxframe
  loop for i = 0 to (n) step 1
    j = i + 1
    print "Plotting points from" (i*5000) " to " (j*5000-1)
    readf data=(file) xcol=1 ycol=2 from=(i*5000) to=(j*5000-1) all accept
    points
  end loop
  endplot
end proc

This would then be invoked as in (assuming the procedure was kept in a file superplot.icl):

ICL > load superplot.icl
ICL > superplot mygalaxies.dat -3 3 -3 3 10

Which would plot $50000$ positions stored in the file mygalaxies.dat.