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1.6 Unconstrained Newton-like optimization

This backend features a Newton-like algorithm. The user has to supply a Hessian function. No constraints are honoured. If the supplied Hessian function actually returns the inverse of the Hessian, set inverse_hessian to true. Supplying the inverse Hessian is preferable, if possible.

Returned value cvg will be 2 or 3 for success and 0 or -1 for failure ( see nonlin_min for meaning). Returned structure outp will have the fields niter, nobjf, and user_interaction.

Interpretation of Display: if set to "iter", some diagnostics are printed.