set terminal png set xlabel "measured $p" set ylabel "calculated $p / measured $p" plot "multiple-version-2.txt" using 1:3 with lines lw 2 title "2 versions" \ , "multiple-version-3.txt" using 1:3 with lines lw 2 title "3 versions" \ , "multiple-version-4.txt" using 1:3 with lines lw 2 title "4 versions" \ , "multiple-version-5.txt" using 1:3 with lines lw 2 title "5 versions" \