keyword:
GRADIENT-ACCURACY-REQUIRED (real)
The optimization will be terminated only when the norm of the
projected gradient
of the merit function - the objective function
in the bound-constrained
case and the augmented Lagrangian function
when there are more general constraints
present - is smaller than a
pre-specified amount (see method section). This accuracy may be
supplied as a real number that follows the keyword
GRADIENT-ACCURACY-REQUIRED. A default
