.. _method-optpp_g_newton-steplength_to_boundary:

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steplength_to_boundary
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Controls how close to the boundary of the feasible region the algorithm is allowed to move


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**Specification**

- *Alias:* None

- *Arguments:* REAL

- *Default:* Merit function dependent: 0.8 (el_bakry), 0.99995 (argaez_tapia), 0.95 (van_shanno)


**Description**


The ``steplength_to_boundary`` specification is a parameter (between 0
and 1) that controls how close to the boundary of the feasible region
the algorithm is allowed to move. A value of 1 means that the
algorithm is allowed to take steps that may reach the boundary of the
feasible region. If the user wishes to maintain strict feasibility of
the design parameters this value should be less than 1. Default values
are .8, .99995, and .95 for the ``el_bakry``, ``argaez_tapia``, and
``van_shanno`` merit functions, respectively.


