%% d'apres les donnees de
%% http://www.mathcurve.com/courbes3d/crepe/crepe.shtml

-2 2 setxrange
-2 2 setyrange
100 setxunit

10 6 6 SetCamPos
0 0 0 SetCamView

-10 10 setxrange3d
-3 3 setyrange3d
2 setlinejoin
rouge

/a 2 def
/b 1 def

/g {
3 dict begin
   settvar
#rpn# a*Cos(t)
#rpn# a*Sin(t)
#rpn# b*Sin(2*t)
end
} def

/g' {
3 dict begin
   settvar
#rpn# -a*Sin(t)
#rpn# a*Cos(t)
#rpn# 2*b*Cos(2*t)
end
} def

/g'' {
3 dict begin
   settvar
#rpn# -a*Cos(t)
#rpn# -a*Sin(t)
#rpn# -4*b*Sin(2*t)
end
} def


0 pi 2 mul {g} CourbeR3
% stop

.3 setlinewidth
%/aretescachees false def
noir

GetCamPos setlightsrc
%solidgridOff

0 pi 2 mul (g) .1 [120 12] newtube
dup (rouge) outputcolors
drawsolid**