Source
45 setxunit
7.5 setborder
90 setangle_repere
-4 6 setxrange
-2.2 3 setyrange
%[1 1 .5 .5 .1 .1] {orange} Quadrillage
1 1 settkstep
traceaxes
axesarrow
/f0 {setxvar
#rpn#   x/(x^2+1)^2
} def
/f1 {setxvar
#rpn#   (x+1)/(x^2+1)^2
} def
/f2 {setxvar
#rpn#   (x+2)/(x^2+1)^2
} def
/f3 {setxvar
#rpn#   (x-1)/(x^2+1)^2
} def
/f4 {setxvar
#rpn#   (x-2)/(x^2+1)^2
} def
/f5 {setxvar
#rpn#   (x+100)/(x^2+1)^2
} def
/f6 {setxvar
#rpn#   (x+50)/(x^2+1)^2
} def
/f7 {setxvar
#rpn#   (x+10)/(x^2+1)^2
} def
/f8 {setxvar
#rpn#   (x-75)/(x^2+1)^2
} def
/f9 {setxvar
#rpn#   (x-20)/(x^2+1)^2
} def
/f10 {setxvar
#rpn#   (x-300)/(x^2+1)^2
} def

gsave
   bleu
   1.5 setlinewidth
   continu
 xmin xmax  {f0} Courbe
 xmin xmax  {f1} Courbe
 xmin xmax  {f2} Courbe
 xmin xmax  {f3} Courbe
 xmin xmax  {f4} Courbe
 xmin xmax  {f5} Courbe
 xmin xmax  {f6} Courbe
 xmin xmax  {f7} Courbe
 xmin xmax  {f8} Courbe
 xmin xmax  {f9} Courbe
 xmin xmax  {f10} Courbe
grestore