#
# Along-path cubic spline smoothing
#
$CURVES << EOD
1 2
1.5 2
2 2.5
3 5
2.5 5
1.5 4
3 3
3.5 3.1
3.7 3.2
3.6 3.7
3.5 4.0
3.2 3.5
3 3
1 5
2 5
3 6
1 5
EOD
set xrange [0:6]
set yrange [0:6.2]
set border 3
set tics nomirror
set style fill transparent solid 0.2 border lt 8
set title "Along-path spline fit to multiple sets of points\n"
plot $CURVES using 1:2 with points ps 2 lc "steelblue" title "original points", \
 '' using 1:2 smooth path with filledcurves closed title "smooth path with filledcurves closed"

Click here for minimal script to generate this plot

$LOOP << EOD
1.5 0.5
2.5 0.5
3 1.0
3.5 1.5
4.0 3.5
3.6 4.5
3.0 2.5
4 1.5
5 1.5
EOD
set title "Along-path spline fit to multiple sets of points\n(some open and some closed)"
plot $CURVES using 1:2 with points pt 7 ps 2 lc "steelblue" title "original points", \
 '' using 1:2 smooth path with lines lt 3 title "smooth path with lines", \
 $LOOP using 1:2 with points pt 7 ps 2 lc "steelblue" notitle, \
 '' using 1:2 smooth path with lines lt 3 notitle

Click here for minimal script to generate this plot