set term post eps enhanced color size 2.5,2.5

set style line 1 lt 1 lc 1 lw 1
set style line 2 lt 1 lc 3 lw 3

set xrange [-2.5:2.5]
set yrange [-2.5:2.5]

set out 'grid1a-img.eps'
plot 'grid1a.dat' w l ls 1 notitle, 'crit1a.dat' w l ls 2 notitle

set out 'grid1a-src.eps'
plot 'grid1a.dat' u 3:4 w l ls 1 notitle, 'crit1a.dat' u 3:4 w l ls 2 notitle

set out 'grid1b-img.eps'
plot 'grid1b.dat' w l ls 1 notitle, 'crit1b.dat' w l ls 2 notitle

set out 'grid1b-src.eps'
plot 'grid1b.dat' u 3:4 w l ls 1 notitle, 'crit1b.dat' u 3:4 w l ls 2 notitle

set term x11