Source
%% PhS
%% fig_Rch06_fin_poly_courbes_param_06

20 setxunit
-4 4  setxrange
-2 3.5 setyrange


%% parametrage de la parabole
/xdet {
1 dict begin
	/t exch def
	t dup mul 3 t mul sub neg
end
	} def


/ydet {
1 dict begin
	/t exch def
	t dup mul
end
	} def


/xpdet {
1 dict begin
	/t exch def
	 t -2 mul 3 add
end} def


/ypdet {
1 dict begin
	/t exch def
	t 2 mul
end
	} def


%% dessine un bout de droite
/bddroite { %% Ax Ay Bx By kg (=proportion vers A) kd (=prop vers B) 
8 dict begin
	/kd exch def
	/kg exch def
	/By exch def
	/Bx exch def
	/B {Bx By} def
	/Ay exch def
	/Ax exch def
	/A {Ax Ay} def
	gsave
	[A A B vecteur kg mulv addv A A B vecteur kd mulv addv] ligne
	grestore
end
	} def


%% definition des points

/M0x {0 xdet} def
/M0y {0 ydet} def
/M0vx {0 xpdet} def
/M0vy {0 ypdet} def



%% definitions des couleurs
%%/coul1 {120 255 div 70 255 div 9 255 div setrgbcolor} def

%% traces
noir
continu
[M0x M0y] points


noir
M0x M0y M0x M0y M0vx M0vy addv -2 2.5 bddroite
M0x M0y M0x M0y -0.1 1 -2 4 bddroite

noir
continu
0 1.7 settrange
{xdet} {ydet} courbeparam
-0.9 0 settrange
{xdet} {ydet neg} courbeparam


noir
1.5 setlinewidth
M0x M0y M0x M0y M0vx M0vy addv (->) line
1.2 setlinewidth
M0x M0y M0x M0y -0.25 2.5 addv (->) line




%% texte
noir
setTimesItalic

  (Point d'inflexion         ) -0.5 -1.5 [1 dup] cctext


%%coul1

<tex>
$ \overrightarrow{f^{(p)}(t_0)} $
</tex>
M0x 2 add M0y 0 add [1 dup] drtexlabel

<tex>
$ \overrightarrow{f^{(q)}(t_0)} $
</tex>
M0x -0.2 add M0y 2 add [1 dup] urtexlabel