%% PhS
%% fig_fct_convexe_01
40 setxunit
-4.5 7 setxrange
-2.3 5.5 setyrange
%% definition des points
/O {0 0} def
/Oxg {-2.5 0} def
/Oxd {7 0} def
/Oyb{0 -3.3} def
/Oyh {0 5.5} def
/Ax {0.4} def
/Ay {Ax -2.3 add dup mul 5 div 1 add} def
/Bx {2.5} def
/By {Bx -2.3 add dup mul 5 div 1 add} def
/Bsy {Bx Ax sub Cx Ax sub div Cy Ay sub mul Ay add} def
/Cx {6} def
/Cy {Cx -2.3 add dup mul 5 div 1 add} def
/A {Ax Ay} def
/B {Bx By} def
/Bs {Bx Bsy} def
/C {Cx Cy} def
%% parametrage de la parabole
/xdet {settvar t t} def
/ydet {settvar t -2.3 add dup mul 5 div 1 add} def
%% traces
continu
[O A B Bs C Ax 0 Bx 0 Cx 0 0 Ay 0 Bsy 0 Cy ] points
[Oxg Oxd] ( ->) ligne
[Oyb Oyh] ( ->) ligne
-1.5 6.5 settrange
{xdet} {ydet} courbeparam
/coul1 {188 255 div 128 255 div 9 255 div setrgbcolor} def
coul1
vert
pointilles
[0 Ay A Ax 0] ligne
[0 Bsy Bs Bx 0] ligne
[0 Cy C Cx 0] ligne
rouge
continu
[A C] ligne
%% texte
setTimesItalic
bleu
(O) O dltext
bleu
<tex>
$ x $
</tex>
Ax -0.6 [1.6 dup] bctexlabel
<tex>
$ \lambda x+(1-\lambda)x' $
</tex>
Bx -0.6 [1.6 dup] bctexlabel
<tex>
$ x' $
</tex>
Cx -0.6 [1.6 dup] bctexlabel
<tex>
$ f(x) $
</tex>
-0.2 Ay [1.6 dup] cltexlabel
<tex>
$ \lambda f(x)+(1-\lambda)f(x') $
</tex>
-0.2 Bsy [1.6 dup] cltexlabel
<tex>
$ f(x') $
</tex>
-0.2 Cy [1.6 dup] cltexlabel
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