\def{text liste= cos(t),sin(t)
t^2,1-t^3
t*sin(t), cos(t)
sin(2*t), cos(2*t)
}
\def{text courbe=randomrow(\liste)}
\def{text f=simplify(item(1,\courbe))}
\def{text g=simplify(item(2,\courbe))}
\def{real a=0}
\def{real b=2*pi}
\def{function df=diff(\f,t)}
\def{function dg=diff(\g,t)}
\def{integer n=10}
\def{text dessin=plot navy, \f,\g}
\for{i=1 to \n}{\def{real c=\a+((\b)-(\a))*\i/\n}
\def{real u=evalue(\f,t=\c)}
\def{real v=evalue(\g,t=\c)}
\def{real u1=\u+evalue(\df,t=\c)}
\def{real v1=\v+evalue(\dg,t=\c)}
\def{text dessin=\dessin
arrow \u,\v,\u1,\v1,5,green
}
}
<center>\draw{200,200}{xrange -3,3
yrange -3,3
arrow 0,0, 0,1,10,black
arrow 0,0, 1, 0 ,10,black
vline 0,0, black
hline 0,0, black
trange \a,\b
\dessin
}</center>
	
