set terminal png
set output "R.png"

set title "Графики относительной погрешности при R=0.5...3"
set ylabel "Относительная погрешность, %"
set xlabel "Коэффициент подобия"

set grid
set xtics 0.005
set ytics 0.02

set parametric
y(t)=t;
set xrange[0.013:0.07]
set yrange[0:0.2]
set trange [0.013:0.07]

plot "R=0,5.txt"    with lines  lw 2 lt rgb 'red'       ti "R = 0.5",\
     "R=1.txt"      with lines  lw 2 lt rgb 'green'     ti "R = 1",\
     "R=1,5.txt"    with lines  lw 2 lt rgb 'brown'     ti "R = 1.5",\
     "R=2.txt"      with lines  lw 2 lt rgb 'purple'    ti "R = 2",\
     "R=2,5.txt"    with lines  lw 2 lt rgb 'orange'    ti "R = 2.5",\
     "R=3.txt"      with lines  lw 2 lt rgb 'blue'      ti "R = 3",\
     y(t), 0.1      notitle     lw 4 lt rgb "black"