# set terminal svg size 600,400 dynamic enhanced fname 'arial'  fsize 10 mousing name "surface1_1" butt solid 
# set output 'surface1.1.svg'
set grid nopolar
set grid xtics nomxtics ytics nomytics noztics nomztics \
 nox2tics nomx2tics noy2tics nomy2tics nocbtics nomcbtics
set grid layerdefault   linetype 0 linewidth 1.000,  linetype 0 linewidth 1.000
set hidden3d back offset 1 trianglepattern 3 undefined 1 altdiagonal bentover
set style data lines
set title "3D surface from a grid (matrix) of Z values" 
set xrange [ -0.500000 : 4.50000 ] noreverse nowriteback
set yrange [ -0.500000 : 4.50000 ] noreverse nowriteback
$grid = <5 line data block>
x = 0.0
splot '$grid' matrix with lines notitle