# set terminal pngcairo  transparent enhanced font "arial,10" fontscale 1.0 size 600, 400 
# set output 'lambert.3.png'
set border -1 front lt black linewidth 1.000 dashtype solid
set view 42, 23, 0.928406, 1.65
set samples 1000, 1000
set isosamples 30, 30
set contour base
set cntrparam levels 11
set cntrparam levels incremental -1,0.2
set cntrparam firstlinetype 101 unsorted
set style data lines
set xzeroaxis
set yzeroaxis
set xyplane at -2
set xtics  norangelimit 0.5 
set title "imag( LambertW( x + iy, 0 ) )" 
set title  offset character 15, 0, 0 font "" textcolor lt -1 norotate
set xrange [ -2.00000 : 1.00000 ] noreverse
set yrange [ -1.00000 : 1.00000 ] noreverse
set zrange [ -2.00000 : 1.80000 ] noreverse
unset colorbox
NO_ANIMATION = 1
splot imag(LambertW( x + I*y, 0 )) lc "cyan" title ""