.. _method-coliny_cobyla-initial_delta:

"""""""""""""
initial_delta
"""""""""""""


Reasonable initial changes to optimization variables


.. toctree::
   :hidden:
   :maxdepth: 1



**Specification**

- *Alias:* None

- *Arguments:* REAL

- *Default:* 1.0 (COBYLA), 0.1*range (PS, SW)


**Description**


``initial_delta`` for COBYLA should be set to be a value that is
reasonable for initial changes to the optimization variables.  It
represents a distance from the initial simplex within which linear
approximation subproblems can be trusted to be sufficiently
representative of the true problem.  It is analagous to the initial
trust-region size used in trust-region methods.


*Default Behavior*

The default value is 1.0.