# set terminal pngcairo  transparent enhanced font "arial,9" fontscale 1.0 size 600, 400 
# set output 'param.1.png'
set dummy t, y
set key bmargin center horizontal Right noreverse enhanced autotitle box linetype -1 linecolor -1 linewidth 1.000
set parametric
set samples 160, 160
set style data lines
plot t,sin(t)/t title "t,sin(t)/t or sin(x)/x"