bound_frac:

Desired minimum relative distance from the initial point to bound. $\;$
Determines how much the initial point might have to be modified in order to be sufficiently inside the bounds (together with "bound_push"). (This is kappa_2 in Section 3.6 of implementation paper.) The valid range for this real option is $0 < {\tt bound\_frac } \le 0.5$ and its default value is $0.01$.