.. _method-nlssol_sqp-convergence_tolerance:

"""""""""""""""""""""
convergence_tolerance
"""""""""""""""""""""


Stopping criterion based on objective function convergence


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**Specification**

- *Alias:* None

- *Arguments:* REAL

- *Default:* 1.e-4


**Description**


The ``convergence_tolerance`` specification provides a real value for
controlling the termination of iteration.

For optimization, it is most commonly a *relative convergence
tolerance* for the objective function; i.e., if the change in the
objective function between successive iterations divided by the
previous objective function is less than the amount specified by
convergence_tolerance, then this convergence criterion is satisfied on
the current iteration.

Therefore, permissible values are between 0 and 1, non-inclusive.

NPSOL defines an internal optimality tolerance which is used in
evaluating if an iterate satisfies the first-order Kuhn-Tucker
conditions for a minimum. The magnitude of ``convergence_tolerance``
approximately specifies the number of significant digits of accuracy
desired in the final objective function (e.g.,
``convergence_tolerance`` = ``1``.0e-6 will result in approximately six
digits of accuracy in the final objective function).