# plot parameter for sp840.f
  set xlabel 'Time difference(sec)'
  set ylabel 'probability (simulation)'
  set xrange[*:*]
  set yrange[1e-6:*]
  set logscale y
  set grid
plot 'sp840.dat' using 1:2 with histeps, \
     'sp820.dat' using 1:2 with histeps, \
     'sp840.dat' using 1:3 with lines