mixed_gradients

Gradients are needed and will be obtained from a mix of numerical and analytic sources

Specification

• Alias: None

• Arguments: None

Child Keywords:

Required/Optional	Description of Group	Dakota Keyword	Dakota Keyword Description
Required		id_numerical_gradients	Identify which numerical gradient corresponds to which response
Required		id_analytic_gradients	Identify which analytical gradient corresponds to which response
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 Type	forward	(Default) Use forward differences
		central	Use central differences
Optional		fd_step_size	Step size used when computing gradients and Hessians

Description

The mixed_gradients specification means that some gradient information is available directly from the simulation (analytic) whereas the rest will have to be finite differenced (numerical). This specification allows the user to make use of as much analytic gradient information as is available and then finite difference for the rest.

The method_source, interval_type, and fd_gradient_step_size specifications pertain to those functions listed by the id_numerical_gradients list.

Examples

For example, the objective function may be a simple analytic function of the design variables (e.g., weight) whereas the constraints are nonlinear implicit functions of complex analyses (e.g., maximum stress).