Blurb::
Gradients are needed and will be obtained from a mix of numerical and
analytic sources
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.
Topics::

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).
Theory::

Faq::

See_Also::
