% Example:
%
% x0 =[1;1]; tol=1e-5; maxiter =10;
% [x,F,iter] = newton_sm(@newton_ff, @newton_df, x0, tol, maxiter);
%
function [x,R,iter] = newton_sm(newton_ff, newton_df, x0, ...
                                tol, nmax, varargin)
iter = 0; err = tol + 1; x = x0;
while err > tol & iter <= nmax
    FF = feval(newton_ff, x, varargin {:});
    DF = feval(newton_df, x, varargin {:});
    delta = - DF\FF;
    x = x + delta;
    err = norm(delta);
    iter = iter + 1;
end
R = norm(feval(newton_ff, x, varargin {:}));
if iter >= nmax
    fprintf('Too many iterations. Residual: %e.\n', R);
else
    fprintf('Success with %i step(s). Residual: %e.\n', iter, R);
end
return