set zero 1e-20
xsm = -1; xla = 1; ysm = -1; yla = 1 
set mxtics 5 ; set mytics 5
set pointsize 1.6
set ticscale  2 1

#set term postscript eps enhanced color solid "Helvetica" 28
#set xlabel "x" 0,0 "Times, 34"
#set ylabel "f(x) and p_n(x)" 1,0 "Times, 34"

set key 0,-0.5
set title "Interpolating polynomial" 0,0 "Times, 18"
set xlabel "x" 0,0 "Times, 18"
set ylabel "f(x) and p_n(x)" 1,0 "Times, 18"

plot [xsm:xla][ysm:yla] \
       'output.dat' u 1:2 t "analytic" w l lw 1 lt -1, \
       'output.dat' u 1:3 t "n=4"   w l lw 1.5 lt 1, \
       'output.dat' u 1:4 t "n=8"   w l lw 1.5 lt 2, \
       'output.dat' u 1:6 t "n=32"  w l lw 1.5 lt 3 

pause -1