# set terminal pngcairo  background "#ffffff" enhanced font "arial,10" fontscale 1.0 size 600, 400 
# set output 'contours.6.png'
set key at screen 1, 0.9, 0 right top vertical Right noreverse enhanced autotitles nobox
set style textbox opaque margins  0.5,  0.5 noborder
set view 60, 30, 1, 1.1
set samples 20, 20
set isosamples 21, 21
set contour surface
set cntrlabel  format '%8.3g' font ',7' start 5 interval 20
set cntrparam levels auto 10
set style data lines
set title "contours drawn on surface" 
set xlabel "X axis" 
set ylabel "Y axis" 
set zlabel "Z " 
set zlabel  offset character 1, 0, 0 font "" textcolor lt -1 norotate
splot x**2-y**2 with lines notitle, x**2-y**2 with lines nosurf lw 3