The GPCG [(ref more-toraldo)] algorithm is much like the TRON algorithm, discussed in
Section , except that
it assumes that the objective function is quadratic and convex.
Therefore, it evaluates the function, gradient, and Hessian only
once.
Since the objective function
is quadratic, the algorithm does not use a trust region.
All of the options that apply to TRON, except for trust region
options, also apply to GPCG.