30 setxunit
7.5 setborder
90 setangle_repere
-5 5 setxrange
-1 6 setyrange
1 1 settkstep
.5 .5 setsubtkstep
1 1 setmkstep
ticks
marks
traceaxes
axesarrow
unites
/f {setxvar
#rpn#   x^2-4
} def
/g {setxvar
#rpn#   4-x^2
} def
/h {setxvar
#rpn#   (x-4)^2
} def
/u {setxvar
#rpn#   5
} def

gsave
   noir
   .75 setlinewidth
   continu
  3 neg  2 neg {f} Courbe
  2  3 {f} Courbe
grestore
gsave
   noir
   .75 setlinewidth
   continu
  2 neg  2 {g} Courbe
grestore
gsave
   noir
   .75 setlinewidth
   continu
  3  5 {h} Courbe
grestore
gsave
   noir
   .75 setlinewidth
   continu
  -5  -3 {u} Courbe
grestore