set terminal svg size 900, 500
set output "mg_with_4_levels6.svg"
set xlabel "Grid points"
set ylabel "Residual value"
set title "Smoothing"
set key outside
set key autotitle columnhead
set pointsize 0.5

plot "mg_with_4_levels.data" index  6 using 1:2 with linespoints lt 3 lw 3