.. index:: single: differential_evolution_problem_protocol
.. _differential_evolution_problem_protocol/0:

.. rst-class:: right

**protocol**

``differential_evolution_problem_protocol``
===========================================

Protocol for continuous bounded Differential Evolution problem definitions.

| **Availability:** 
|    ``logtalk_load(differential_evolution(loader))``

| **Author:** Paulo Moura
| **Version:** 1:0:0
| **Date:** 2026-08-13

| **Compilation flags:**
|    ``static``


| **Dependencies:**
|   (none)


| **Remarks:**
|    (none)

| **Inherited public predicates:**
|    (none)

.. contents::
   :local:
   :backlinks: top

Public predicates
-----------------

.. index:: position_bounds/1
.. _differential_evolution_problem_protocol/0::position_bounds/1:

``position_bounds/1``
^^^^^^^^^^^^^^^^^^^^^

Returns one ``Lower-Upper`` numeric bound pair per dimension, with ``Lower =< Upper``.

| **Compilation flags:**
|    ``static``

| **Template:**
|    ``position_bounds(Bounds)``
| **Mode and number of proofs:**
|    ``position_bounds(-list(pair))`` - ``one``


------------

.. index:: fitness/2
.. _differential_evolution_problem_protocol/0::fitness/2:

``fitness/2``
^^^^^^^^^^^^^

Computes the fitness of a candidate solution. The optimization direction is selected by the ``objective/1`` option.

| **Compilation flags:**
|    ``static``

| **Template:**
|    ``fitness(Position,Fitness)``
| **Mode and number of proofs:**
|    ``fitness(+list(number),-number)`` - ``one``


------------

.. index:: initial_positions/1
.. _differential_evolution_problem_protocol/0::initial_positions/1:

``initial_positions/1``
^^^^^^^^^^^^^^^^^^^^^^^

Optional. Returns a non-empty list of initial positions. When not defined, the algorithm generates a random initial population inside the position bounds.

| **Compilation flags:**
|    ``static``

| **Template:**
|    ``initial_positions(Positions)``
| **Mode and number of proofs:**
|    ``initial_positions(-list(list(number)))`` - ``zero_or_one``


------------

.. index:: stop_condition/3
.. _differential_evolution_problem_protocol/0::stop_condition/3:

``stop_condition/3``
^^^^^^^^^^^^^^^^^^^^

Optional. True when the search should stop given the completed generation, best position, and best fitness.

| **Compilation flags:**
|    ``static``

| **Template:**
|    ``stop_condition(Generation,BestPosition,BestFitness)``
| **Mode and number of proofs:**
|    ``stop_condition(+non_negative_integer,+list(number),+number)`` - ``zero_or_one``


------------

.. index:: progress/5
.. _differential_evolution_problem_protocol/0::progress/5:

``progress/5``
^^^^^^^^^^^^^^

Optional. Called periodically with generation, best position, best fitness, mean population fitness, and population diversity (mean Euclidean distance from the centroid).

| **Compilation flags:**
|    ``static``

| **Template:**
|    ``progress(Generation,BestPosition,BestFitness,MeanFitness,Diversity)``
| **Mode and number of proofs:**
|    ``progress(+non_negative_integer,+list(number),+number,+number,+number)`` - ``zero_or_one``


------------

Protected predicates
--------------------

(none)

Private predicates
------------------

(none)

Operators
---------

(none)

.. seealso::

   :ref:`differential_evolution(Problem) <differential_evolution/1>`, :ref:`differential_evolution(Problem,RandomAlgorithm) <differential_evolution/2>`