set term postscript color enhanced  'Times-Roman' 22
!rm ring_twiss.ps
set output 'ring_twiss.ps'
set xlabel 's[m]'
set ylabel '{/Symbol b}'
set y2label '{/Symbol h}[m]'
set xrange [0:]
set yrange [0:]
set key bottom right Left 
plot 'twiss_file.dat' u 2:4 w l lw 2 lt 1 lc 2 t '{/Symbol b}_x',\
'twiss_file.dat' u 2:6 w l lw 2 lt 1 lc 1 t '{/Symbol b}_y',\
'twiss_file.dat' u 2:8 w l lw 2 lt 1 lc 3 t '{/Symbol h}_x'