 damped_newton(4) damped Newton nonlinear algorithm

## DESCRIPTION

Nonlinear damped Newton algorithm for the resolution of the following problem:

```       F(u) = 0

```
A simple call to the algorithm writes:

```    my_problem P;
field uh (Vh);
damped_newton (P, uh, tol, max_iter);

```
The my_problem class may contains methods for the evaluation of F (aka residue) and its derivative:

```    class my_problem {
public:
my_problem();
field residue (const field& uh) const;
void update_derivative (const field& uh) const;
field derivative_trans_mult (const field& mrh) const;
field derivative_solve (const field& mrh) const;
Float norm (const field& uh) const;
Float dual_norm (const field& Muh) const;
};

```
See the example p-laplacian.h in the user's documentation for more.

## IMPLEMENTATION

```template <class Problem, class Field, class Real, class Size>
int damped_newton (Problem P, Field& u, Real& tol, Size& max_iter, odiststream* p_derr=0) {
return damped_newton(P, newton_identity_preconditioner(), u, tol, max_iter, p_derr);
}

```