Source
%% PhS
%%

40 setxunit
-3 7  setxrange
-2.5 4.5 setyrange

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% definition des points
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

/p {1.5} def
/e {0.7} def
/F {0 0} def
/Kx {p e div neg} def
/K {Kx 0} def
/D {Kx -2.2} def
/H1 {-8 0} def
/H2 {8 0} def
/V1 {Kx -3.5} def
/V2 {Kx 5} def

/rhox {settvar t cos e mul neg 1 add 1 exch div p mul t cos mul} def
/rhoy {settvar t cos e mul neg 1 add 1 exch div p mul t sin mul} def

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% definition d'une couleur
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

/coul1 {120 255 div 70 255 div 9 255 div setrgbcolor} def

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% tracés
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
1.3 setlinewidth
continu
[K F] points
[H1 H2] ligne
[V1 V2] ligne

coul1
0 380 settrange
{rhox} {rhoy} courbeparam

rouge
[F F 1 0 addv] ( ->) ligne
[F F 0 1 addv] ( ->) ligne

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% texte
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

setTimesItalic
noir
(K) K [1.5 dup] dltext

rouge
(F) F [1.5 dup] dtext

noir
<latex>
$\mathcal{D}$
</latex>
D [1.5 dup] ultexlabel

rouge
<latex>
$\vec{\imath}$
</latex>
F 0.8 -0.2 addv [1.5 dup] cctexlabel

<latex>
$\vec{\jmath}$
</latex>
F -0.2 0.7 addv [1.5 dup] cctexlabel

noir
<latex>
\fbox{$\rho(\theta)=\displaystyle\frac{p}{1-e\cos(\theta)}$}
</latex>
4 3.5 [1.5 dup] cctexlabel