input newcourbes;
input couleur;
input geometriesyr16;
input TEX;


verbatimtex
%&latex
\documentclass{article}
\usepackage[upright]{fourier}
\usepackage{color}
\def\E{\mathrm{e}}
\let\ve\vec
\def\DR{\mathcal{D}}
\def\CR{\mathcal{C}}
\def\HR{\mathcal{H}}
\newcommand{\Mathbold}[1]{\mbox{\boldmath$#1$\unboldmath}}
\begin{document}
etex
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% S P I R A L E

beginfig(8)

numeric u;
u:=1cm;

pair a[],o,s;

s:=(1,-1);
o:=origin;
a[0]:=(0,-u);
for i=0 upto 5 :
a[i+1]:=a[i] zscaled s;
endfor

draw o--a[0] dashed evenly;
for i=1 upto 6 :
draw o--a[i] dashed evenly;

draw a[i-1]--a[i] withcolor 0.6white withpen pencircle scaled 2bp;

draw symbole_ortho(o,a[i-1],a[i],0.25u);

draw_marks(o--a[i-1],i);
draw_marks(a[i-1]--a[i],i);

endfor

endfig;

end