# set terminal png transparent nocrop enhanced font arial 8 size 420,320 
# set output 'polar.5.png'
set clip points
unset border
set dummy t,y
set key right top Right noreverse noinvert enhanced box linetype -1 linewidth 1.000 samplen 4 spacing 1 width 0 height 0 autotitles
set polar
set samples 160, 160
set xzeroaxis lt 0 lw 1.000
set yzeroaxis lt 0 lw 1.000
set xtics axis nomirror norotate autofreq 
set ytics axis nomirror norotate autofreq 
set trange [ 0.00000 : 6.28319 ] noreverse nowriteback
set xrange [ -5.00000 : 5.00000 ] noreverse nowriteback
set yrange [ -5.00000 : 5.00000 ] noreverse nowriteback
plot t/cos(3*t)