set xrange [-pi:pi]
set xtics ("-{/Symbol p}" -pi, "-{/Symbol p}/2" -pi/2, "0" 0,\
           "{/Symbol p}/2" pi/2, "{/Symbol p}" pi )  
set ytics add ( "{/=16 -e/2}" -exp(1)/2, "{/Symbol \326}2" sqrt(2) )
set grid
set term pngcairo enh font "Helvetica,14" size 480,360
set out "format_label.png"
plot 3*sin(2*x)