File:Piecewise linear function gnuplot.svg

set xrange [-5:5]
set yrange [-3:3]
set xtics 1
set ytics 1

f(x) =  (            x <= -3    ? -3 - x        \   
        : -3 <= x && x <=  0    ? x + 3         \   
        :  0 <= x && x <=  3    ? 3 - 2*x       \   
        :                         0.5*x - 4.5   \   
        )

set grid

# y axis
set arrow from 0,-3 to 0,3 nohead lt 8

#x axis
  plot           0    with lines lt 8 lw 1 title ""

# plot the function
#replot           f(x) with lines lt 6 lw 3 title ""

# plot the function in pieces to avoid artifacts at interval boundaries
replot [x=-5:-3] f(x) with lines lt 6 lw 3 title ""
replot [x=-3: 0] f(x) with lines lt 6 lw 3 title ""
replot [x= 0: 3] f(x) with lines lt 6 lw 3 title ""
replot [x= 3: 5] f(x) with lines lt 6 lw 3 title ""
pause -1