# set terminal png transparent nocrop enhanced font arial 8 size 420,320 
# set output 'param.5.png'
set dummy t,y
set key bmargin center horizontal Right noreverse enhanced autotitles box linetype -1 linewidth 1.000
set parametric
set samples 160, 160
set xrange [ -5.00000 : 5.00000 ] noreverse nowriteback
set yrange [ -5.00000 : 5.00000 ] noreverse nowriteback
plot tan(t),t,t,tan(t)