# set terminal svg size 600,400 dynamic enhanced fname 'arial'  fsize 10 mousing name "hidden_1" butt solid 
# set output 'hidden.1.svg'
set samples 20, 20
set isosamples 20, 20
set hidden3d back offset 1 trianglepattern 3 undefined 1 altdiagonal bentover
set title "Hidden line removal of explicit surfaces" 
set xrange [ -3.00000 : 3.00000 ] noreverse nowriteback
set yrange [ -2.00000 : 2.00000 ] noreverse nowriteback
splot 1 / (x*x + y*y + 1)