TOL = 1E-6;
deff("y = fn(x)","y =  x - 0.2*sin(x) - 0.5") 
xavder = input("abscisse gauche: "); 
xder = input("abscisse droite: "); 
favder = fn(xavder); fder = fn(xder);
while abs(xder - xavder) > TOL 
    x = xder - fder*(xder-xavder)/(fder-favder);
    f = fn(x);
    favder = fder; xavder = xder;
    xder = x; fder = f;
end
x = xder - fder*(xder-xavder)/(fder-favder) ;
mprintf("racine: %14.8f\tvaleur de la fonction:%14.8f\n",x,fn(x));