This function implements a generic damped Newton method for the resolution of the following problem:
F(lambda,u) = 0
where lambda is a parameter and u is the corresponding solution, that depends upon lambda. The main idea
is to follow a branch of solution denoted as u(lambda) when the parameter lambda varies. A simple call to
the algorithm writes:
my_problem P;
field uh (Vh,0);
continuation (P, uh, &dout, &derr);
The optional argument continuation_option(3) allows one to control some features of the algorithm.
The continuation algorithm bases on the damped_newton(3) method. In addition to the members required for
the damped_newton(3) method, several additional members are required for the continuation one. The
requirements are:
class my_problem {
public:
typedef float_type;
typedef value_type;
string parameter_name() const;
float_type parameter() const;
void set_parameter (float_type lambda);
value_type residue (const value_type& uh) const;
void update_derivative (const value_type& uh) const;
csr<float_type> derivative (const value_type& uh) const;
value_type derivative_solve (const value_type& mrh) const;
value_type derivative_trans_mult (const value_type& mrh) const;
value_type derivative_versus_parameter (const field& uh) const;
bool stop (const value_type& xh) const;
idiststream& get (idiststream& is, value_type& uh);
odiststream& put (odiststream& os, const value_type& uh) const;
float_type space_norm (const value_type& uh) const;
float_type dual_space_norm (const value_type& mrh) const;
float_type space_dot (const value_type& xh, const value_type& yh) const;
float_type dual_space_dot (const value_type& mrh, const value_type& msh) const;
value_type massify (const value_type& uh) const;
value_type unmassify (const value_type& mrh) const;
};