Source
%% auteur : 

80 setxunit %% 10 mm
%[1 1] {.4 setgray} Quadrillage

-0.5 5 setxrange
-0.5 8 setyrange
[1 1 .5 .5 .1 .1] {.4 setgray} Quadrillage
 1.3 setlinewidth
tracerepere
15 setfontsize
marks
 traceaxes
axesarrow
setTimes
(O) O [1.5 1.5] dltext

/f {setxvar
    3 0.5 x exp mul
} def
   
   1.2 setlinewidth
   continu
 0 4  {f} Courbe
0 3 point
1 1.5 point 
2 0.75 point
3 0.375 point
4 0.1875 point
/g {setxvar
    2} def
   
   1.2 setlinewidth
   continu
 0 4  {g} Courbe

0 2 point
1 2 point
2 2 point
3 2 point
 4 2 point


/h {setxvar
    2 x exp} def
   
   1.2 setlinewidth
   continu
 0 4  {h} Courbe

0 1 point
1 2 point
2 4 point

<tex>
$b<1$ 
</tex>
3.5 0.7 [2 dup] dctexlabel


<tex>
$b=1$ 
</tex>
3.5 2 [2 dup] dctexlabel



<tex>
$b>1$ 
</tex>
3 6 [2 dup] dctexlabel