set samples 2001 set terminal svg set output "gunn.svg"  # VI curve with negative differential resistance region I(V) = (V/2.5-2)**3 + -2*(V/2.5-2) + 4  # Square plot ratio set size square  # Set range of x and y axes set xrange [0:10] set yrange [0:10]  # Create axis tics every 20 numbers, so only the 0 is actually visible set xtics 20 set ytics 20  # Use 10 axis minor divisions per major division, so there is a division for each integer, but they aren't labeled. set mxtics 20 set mytics 20  # Axis labels set xlabel "Voltage (V)" set ylabel "Current (I)"  # VI curve's plotting style set style line 1 lt 1 lw 2  # Dotted line style set style line 2 lt 2 lw 1  set style arrow 2 nohead ls 2  # Draw dotted lines set arrow 1 from 3,5.3 to 3,7 as 2 set arrow 2 from 7,3.1 to 7,7 as 2  # Arrowheaded line style set style line 4 lt 4 lw 1 set style arrow 4 head filled size screen 0.02,15,45 ls 4  # Draw arrows set arrow 3 from 3.7,7 to 3,7 as 4 set arrow 4 from 6.3,7 to 7,7 as 4  # Label region set label 1 "Negative differential \nresistance region" at 5,8 c  # Plot the filter response plot I(x) ls 1 notitle