.. _method-multifidelity_sampling-numerical_solve-model_reordering-fixed_order:

"""""""""""
fixed_order
"""""""""""


Enforce a prescribed model ordering in MFMC numerical solutions through additional linear constraints.



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



**Specification**

- *Alias:* None

- *Arguments:* None


**Description**


A model hierarchy is prescribed for MFMC according to the model order
given in the ensemble surrogate model specification.  Additional
linear constraints enforce that sample allocations are strictly
decreasing across the model order from lowest to highest fidelity.

The solution provided is optimal for the MFMC estimator given the
prescribed model ordering.  Allowing model reordering on the fly
(the default behavior) may result in lower estimator variance, but
can complicate comparisons with published MFMC implementations.




**Examples**



.. code-block::

    method,
	multifidelity_sampling
	numerical_solve override
	  model_reordering fixed_order   # optional approach
	solution_mode online_pilot
	pilot_samples = 50 seed = 8674132
	max_function_evaluations = 500