set term postscript enhanced color 20
#
# our output goes straight to a postscript file called print.ps
#
set output "print.ps"
set pointsize 1.8
#
# create two types of line-styles, with different colours 
#
set style line 1 lt 3 lw 3 pt 3 
set style line 2 lt 1 lw 3 pt 3 
# title 
set title "Solution to the 2nd-order ODE"
#set key 0.23, -7
# x and y labels
set xlabel "x"; set ylabel "y"
# plot 
plot "exact.dat" using ($1):($2) title "exact solution" with l ls 1\
  , "rk.dat" using ($1):($2) title "Runge-Kutta" with l ls 2