# MDO Formulation algorithms¶

Warning

Some algorithms may require the installation of GEMSEO with all its features and some others may depend on plugins.

Note

All the features of the wrapped optimization libraries may not be exposed through GEMSEO.

## BiLevel¶

Required parameters
• design_space : DesignSpace

The design space.

• disciplines : Sequence[MDODiscipline]

The disciplines.

• objective_name : str

The name of the objective function. If a sequence is passed, a vector objective function is created.

Optional parameters
• apply_cstr_to_system : bool, optional

Whether the add_constraint() method adds the constraint to the optimization problem of the system scenario.

By default it is set to True.

• apply_cstr_tosub_scenarios : bool, optional

Whether the add_constraint() method adds the constraint to the optimization problem of the sub-scenario capable of computing the constraint.

By default it is set to True.

• grammar_type : str, optional

The type of the input and output grammars, either MDODiscipline.JSON_GRAMMAR_TYPE or MDODiscipline.SIMPLE_GRAMMAR_TYPE.

By default it is set to JSONGrammar.

• inner_mda_name : str, optional

The name of the class used for the inner-MDA of the main MDA, if any; typically when the main MDA is an MDAChain.

By default it is set to MDAJacobi.

• main_mda_name : str, optional

The name of the class used for the main MDA, typically the MDAChain, but one can force to use MDAGaussSeidel for instance.

By default it is set to MDAChain.

• maximize_objective : bool, optional

If True, the objective function is maximized.

By default it is set to False.

• multithread_scenarios : bool, optional

If True and parallel_scenarios=True, the sub-scenarios are run in parallel using multi-threading; if False and parallel_scenarios=True, multi-processing is used.

By default it is set to True.

• parallel_scenarios : bool, optional

Whether to run the sub-scenarios in parallel.

By default it is set to False.

• reset_x0_before_opt : bool, optional

Whether to restart the sub optimizations from the initial guesses, otherwise warm start them.

By default it is set to False.

• **main_mda_options : Any

The options of the main MDA, which may include those of the inner-MDA.

## DisciplinaryOpt¶

Required parameters
• design_space : DesignSpace

The design space.

• disciplines : Sequence[MDODiscipline]

The disciplines.

• objective_name : str

The name of the objective function. If a sequence is passed, a vector objective function is created.

Optional parameters

## IDF¶

Required parameters
• design_space : DesignSpace

The design space.

• disciplines : Sequence[MDODiscipline]

The disciplines.

• objective_name : str

The name of the objective function. If a sequence is passed, a vector objective function is created.

Optional parameters
• grammar_type : str, optional

The type of the input and output grammars, either MDODiscipline.JSON_GRAMMAR_TYPE or MDODiscipline.SIMPLE_GRAMMAR_TYPE.

By default it is set to JSONGrammar.

• maximize_objective : bool, optional

If True, the objective function is maximized.

By default it is set to False.

• n_processes : int, optional

The maximum simultaneous number of threads, if use_threading is True, or processes otherwise, used to parallelize the execution.

By default it is set to 1.

• normalize_constraints : bool, optional

If True, the outputs of the coupling consistency constraints are scaled.

By default it is set to True.

• start_at_equilibrium : bool, optional

If True, an MDA is used to initialize the coupling variables.

By default it is set to False.

• use_threading : bool, optional

Whether to use threads instead of processes to parallelize the execution; multiprocessing will copy (serialize) all the disciplines, while threading will share all the memory. This is important to note if you want to execute the same discipline multiple times, you shall use multiprocessing.

By default it is set to True.

## MDF¶

Required parameters
• design_space : DesignSpace

The design space.

• disciplines : Sequence[MDODiscipline]

The disciplines.

• objective_name : str

The name of the objective function. If a sequence is passed, a vector objective function is created.

Optional parameters
• grammar_type : str, optional

The type of the input and output grammars, either MDODiscipline.JSON_GRAMMAR_TYPE or MDODiscipline.SIMPLE_GRAMMAR_TYPE.

By default it is set to JSONGrammar.

• inner_mda_name : str, optional

The name of the class used for the inner-MDA of the main MDA, if any; typically when the main MDA is an MDAChain.

By default it is set to MDAJacobi.

• main_mda_name : str, optional

The name of the class used for the main MDA, typically the MDAChain, but one can force to use MDAGaussSeidel for instance.

By default it is set to MDAChain.

• maximize_objective : bool, optional

If True, the objective function is maximized.

By default it is set to False.

• **main_mda_options : Any

The options of the main MDA, which may include those of the inner-MDA.