set output 'waves_out_phase.ps' 
set term postscript color enhanced  
set grid 
set key top right 
set size square 
set xlabel '' 
set ylabel '' 
set title 'Two waves moving out of phase '
plot [-5:12][-1.5:2.0]  'wave_phase.dat' using 1:2 with linespoints lt 1 lw 5 t ''   ,  'wave_phase.dat' using 1:5 with linespoints ps 1 pt 3 lw 3 t ''   
set output 
quit 
