set term svg size 800,600 font 'Times,18' fsize 18;
set out 'plot.svg';
set key bottom;
set tics out;
set xlabel 'x';
set ylabel 'y';
set title 'Linear/quadratic/cubic splines of some random data';
plot   'out.data.txt' index 0 with points pointtype 7 title 'data',
'out.data.txt' index 1 using 1:2 with lines title 'linear',
'out.data.txt' index 1 using 1:3 with lines title 'quadratic',
'out.data.txt' index 1 using 1:4 with lines title 'cubic',
'out.data.txt' index 0 smooth csplines lw 4 dashtype (10,10) title 'gnuplot cubic spline'