.. _model-surrogate-global-experimental_gaussian_process-trend:

"""""
trend
"""""


This keyword enables the use of deterministic polynomial trend function


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

   model-surrogate-global-experimental_gaussian_process-trend-none
   model-surrogate-global-experimental_gaussian_process-trend-constant
   model-surrogate-global-experimental_gaussian_process-trend-linear
   model-surrogate-global-experimental_gaussian_process-trend-reduced_quadratic
   model-surrogate-global-experimental_gaussian_process-trend-quadratic


**Specification**

- *Alias:* None

- *Arguments:* None

- *Default:* reduced_quadratic


**Child Keywords:**

+-------------------------+--------------------+-----------------------+-----------------------------------------------+
| Required/Optional       | Description of     | Dakota Keyword        | Dakota Keyword Description                    |
|                         | Group              |                       |                                               |
+=========================+====================+=======================+===============================================+
| Required (Choose One)   | Trend Order        | `none`__              | No trend function                             |
|                         |                    +-----------------------+-----------------------------------------------+
|                         |                    | `constant`__          | Constant trend function                       |
|                         |                    +-----------------------+-----------------------------------------------+
|                         |                    | `linear`__            | Use a linear polynomial or trend function     |
|                         |                    +-----------------------+-----------------------------------------------+
|                         |                    | `reduced_quadratic`__ | Quadratic polynomials - main effects only     |
|                         |                    +-----------------------+-----------------------------------------------+
|                         |                    | `quadratic`__         | Use a quadratic polynomial or trend function  |
+-------------------------+--------------------+-----------------------+-----------------------------------------------+

.. __: model-surrogate-global-experimental_gaussian_process-trend-none.html
__ model-surrogate-global-experimental_gaussian_process-trend-constant.html
__ model-surrogate-global-experimental_gaussian_process-trend-linear.html
__ model-surrogate-global-experimental_gaussian_process-trend-reduced_quadratic.html
__ model-surrogate-global-experimental_gaussian_process-trend-quadratic.html



**Description**


Enable the use of a deterministic polynomial trend function whose coefficients are
found through regression. The user may choose a constant, linear, or quadratic
polynomial.

*Default Behavior*
Defaults to no trend when keyword is absent.


