gnuplot> set output "/tmp/out.png"
gnuplot> set terminal png transparent
Terminal type set to 'png'
Options are 'transparent small color picsize 640 480 '
gnuplot> plot [-10:10] f(x) = (1-x**2)/(4-x**2), f(x) title "f(x)=(1-x**2)/(4-x**2)"
gnuplot>
Результат:
