Created by User:Omegatron using gnuplot, possibly with post-processing in the GIMP (PNG) or Inkscape (SVG)

(In short, this means that you can copy and modify the image freely as long as you provide attribution; preferably in the form of a link back to this page.)

See Wikipedia graph-making tips.

 # Set square ×ばつ1000 SVG output and filename
 # The font size (fsize) sets the size for the circles, too.
 set terminal svg enhanced size 1000 1000 fname "Times" fsize 36
 set output "floor.svg"
 # Set the text value for missing entries in the data file, so we can plot a [[w:discontinuous function|discontinuous function]]
 set datafile missing "Skip"
 # Set y axis limits so the plot doesn't go right to the edges of the graph
 set yrange [-3.5:3.5]
 # Set x axis limits so the first and last points are hidden
 set xrange [-3.5:3.5]
 # No legend needed
 set nokey
 # Add lightly-colored axis lines
 set yzeroaxis
 set xzeroaxis
 # Plot as lines and also points (circles)
 plot "floor.dat" with lines
 plot "floor.dat" with points 1 6
 # Close the file (so I don't have to close gnuplot to view it)
 set output

and data file:

floor.dat

# X Y1
 -3 -4
 Skip
 -3 -3
 -2 -3
 Skip
 -2 -2
 -1 -2
 Skip
 -1 -1
 0 -1
 Skip
 0 0
 1 0
 Skip
 1 1
 2 1
 Skip
 2 2
 3 2
 Skip
 3 3
 4 3

Then I opened the resulting SVG file in Inkscape, changed the fill style for the circles (either blue or white fill), brought the plot lines to the top, and then brought the circles to the top (over the lines).

• Mathworld's version