.. _responses-numerical_gradients:

"""""""""""""""""""
numerical_gradients
"""""""""""""""""""


Gradients are needed and will be approximated by finite differences


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

   responses-numerical_gradients-method_source
   responses-numerical_gradients-dakota
   responses-numerical_gradients-vendor
   responses-numerical_gradients-interval_type
   responses-numerical_gradients-forward
   responses-numerical_gradients-central
   responses-numerical_gradients-fd_step_size


**Specification**

- *Alias:* None

- *Arguments:* None


**Child Keywords:**

+-------------------------+--------------------+--------------------+-----------------------------------------------+
| Required/Optional       | Description of     | Dakota Keyword     | Dakota Keyword Description                    |
|                         | Group              |                    |                                               |
+=========================+====================+====================+===============================================+
| Optional                                     | `method_source`__  | Specify which finite difference routine is    |
|                                              |                    | used                                          |
+-------------------------+--------------------+--------------------+-----------------------------------------------+
| Optional (Choose One)   | Gradient Source    | `dakota`__         | (Default) Use internal Dakota finite          |
|                         |                    |                    | differences algorithm                         |
|                         |                    +--------------------+-----------------------------------------------+
|                         |                    | `vendor`__         | Use non-Dakota fd algorithm                   |
+-------------------------+--------------------+--------------------+-----------------------------------------------+
| Optional                                     | `interval_type`__  | Specify how to compute gradients and hessians |
+-------------------------+--------------------+--------------------+-----------------------------------------------+
| Optional (Choose One)   | Finite Difference  | `forward`__        | (Default) Use forward differences             |
|                         | Type               +--------------------+-----------------------------------------------+
|                         |                    | `central`__        | Use central differences                       |
+-------------------------+--------------------+--------------------+-----------------------------------------------+
| Optional                                     | `fd_step_size`__   | Step size used when computing gradients and   |
|                                              |                    | Hessians                                      |
+----------------------------------------------+--------------------+-----------------------------------------------+

.. __: responses-numerical_gradients-method_source.html
__ responses-numerical_gradients-dakota.html
__ responses-numerical_gradients-vendor.html
__ responses-numerical_gradients-interval_type.html
__ responses-numerical_gradients-forward.html
__ responses-numerical_gradients-central.html
__ responses-numerical_gradients-fd_step_size.html



**Description**


The ``numerical_gradients`` specification means that gradient
information is needed and will be computed with finite differences
using either the native or one of the vendor finite differencing
routines.


