%% auteur : gh

120 setxunit
-0.5 2.5 setxrange
-1.5 1.5 setyrange

traceaxes
axesarrow

/O {0 0} def
16 setfontsize
setTimesItalic
   (O) O dltext

/rho {Cos 1 add} def
/rho' {Sin neg} def

/X {dup rho exch Cos mul} def
/Y {dup rho exch Sin mul} def

/X' {settvar t rho' t Cos mul t rho t Sin mul sub} def
/Y' {settvar t rho' t Sin mul t rho t Cos mul add} def

orange
1 setcurvelinewidth
pi pi 2 mul settrange
{X} {Y} courbeparam

1.7 setcurvelinewidth
rouge
0 pi settrange
{X} {Y} courbeparam


bleu
0.4 settailletangente
1 setlinewidth
0 (X)(Y) ptangente 
pi 2 div (X)(Y) ptangente 
%% pi (X)(Y) ptangente [POINT SINGULIER !]
-0.2 0 0.2 0 (<->) line

noir
<tex>
$$ M(0) $$
</tex>
0 X 0 Y [1.3 1.3] ultexlabel
<tex>
$$ M(\pi /2) $$
</tex>
pi 2 div X pi 2 div Y [1.3 1.3] ultexlabel
<tex>
$$ M(\pi) $$
</tex>
pi X pi Y [1.3 1.3] urtexlabel