Differential Evolution Optimizer Class
Definition
Assembly: Numerics.NET (in Numerics.NET.dll) Version: 9.1.0
public sealed class DifferentialEvolutionOptimizer : PopulationBasedOptimizer<Population<Candidate>, Candidate>
- Inheritance
- Object → ManagedIterativeAlgorithm<Vector<Double>, Double, OptimizationSolutionReport<Vector<Double>>> → MultidimensionalOptimizer<Vector<Double>, OptimizationSolutionReport<Vector<Double>>> → PopulationBasedOptimizer<Vector<Double>, Population<Candidate>, Candidate> → PopulationBasedOptimizer<Population<Candidate>, Candidate> → DifferentialEvolutionOptimizer
Remarks
Use the DifferentialEvolutionOptimizer class to find an extremum of an objective function through population-based evolutionary optimization. The algorithm maintains a population of candidate solutions and creates new candidates through mutation and crossover operations.
The main advantage of this method is its robustness and ability to find global optima for non-convex, non-linear, and multimodal functions. It requires minimal tuning of control parameters and does not use gradient information.
The objective function must be supplied as a multivariate function delegate to the ObjectiveFunction property.
Before the algorithm is run, you must set the LowerBounds and UpperBounds properties to specify the search space constraints. The ExtremumType property specifies whether a minimum or a maximum of the objective function is desired.
Example
The following example attempts to find a minimum for the Rastrigin function using the Differential Evolution optimizer.
The Rastrigin function is a challenging test problem for global optimization algorithms. The function has many local minima, which makes it tricky for an optimizer to find the global minimum.
// Define the Rastrigin function
Func<Vector<double>, double> rastrigin = (x) =>
{
int n = x.Length;
double A = 10;
double sum = A * n;
for (int i = 0; i < n; i++)
{
sum += x[i] * x[i] - A * Math.Cos(2 * Math.PI * x[i]);
}
return sum;
};
// Define the lower and upper bounds
Vector<double> lowerBounds = Vector.Create<double>(-5.12, -5.12);
Vector<double> upperBounds = Vector.Create<double>(5.12, 5.12);
// Create the optimizer
var optimizer = new DifferentialEvolutionOptimizer(
objectiveFunction: rastrigin,
lowerBounds: lowerBounds,
upperBounds: upperBounds
);
// Run the optimization
optimizer.FindMinimum();
// Get the result
Vector<double> solution = optimizer.Extremum;
double value = optimizer.ValueAtExtremum;
Constructors
Differential | Constructs a new DifferentialEvolutionOptimizer object. |
Differential | Constructs a new Differential Evolution optimizer with specified parameters. |
Properties
Convergence |
Gets the collection of convergence tests for the algorithm.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>) |
Crossover | Gets or sets the crossover rate used in the algorithm. |
Differential | Gets or sets the differential weight factor used in the mutation step. |
Dimensions |
Gets or sets the number of dimensions of the optimization problem.
(Inherited from PopulationBasedOptimizer<TPopulation, TCandidate>) |
Dithering | Gets or sets the dithering range used when WeightDithering is set to Uniform. |
Diversity |
Gets the convergence test that measures population diversity.
(Inherited from PopulationBasedOptimizer<TSolution, TPopulation, TCandidate>) |
Estimated |
Gets a value indicating the size of the absolute
error of the result.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>) |
Evaluations |
Gets the number of evaluations needed to execute the algorithm.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>) |
Extremum |
Gets or sets the current best approximation to the extremum.
(Inherited from MultidimensionalOptimizer<T, TReport>) |
Extremum |
Gets or sets the type of extremum.
(Inherited from MultidimensionalOptimizer<T, TReport>) |
Has |
Indicates whether the degree of parallelism is a property that is shared
across instances.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>) |
Initial |
Gets or sets the initial value for the iteration.
(Inherited from MultidimensionalOptimizer<T, TReport>) |
Initialization |
Gets or sets the method used to initialize the population.
(Inherited from PopulationBasedOptimizer<TPopulation, TCandidate>) |
Iterations |
Gets the number of iterations needed by the
algorithm to reach the desired accuracy.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>) |
Lower |
Gets or sets the vector of lower bounds for the solution.
(Inherited from PopulationBasedOptimizer<TPopulation, TCandidate>) |
Max |
Gets or sets the maximum degree of parallelism enabled by this instance.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>) |
Max |
Gets or sets the maximum number of evaluations during the calculation.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>) |
Max | Gets or sets the maximum number of iterations
to use when approximating the roots of the target
function.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>) |
Min |
Gets or sets the minimum iterations that have to be performed.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>) |
Mutation | Gets or sets the mutation strategy used to generate trial vectors. |
Objective |
Gets or sets the objective function.
(Inherited from MultidimensionalOptimizer<T, TReport>) |
Parallel |
Gets or sets the configuration for the parallel behavior of the algorithm.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>) |
Population |
Gets the current population of solutions.
(Inherited from PopulationBasedOptimizer<TSolution, TPopulation, TCandidate>) |
Population |
Gets the convergence test that uses the population's coefficient of variation.
(Inherited from PopulationBasedOptimizer<TSolution, TPopulation, TCandidate>) |
Population | Gets or sets the population multiplier used to determine the population size. |
Population |
Gets or sets the population size used in the algorithm.
(Inherited from PopulationBasedOptimizer<TSolution, TPopulation, TCandidate>) |
Random |
Gets or sets the random number generator used by the optimizer.
(Inherited from PopulationBasedOptimizer<TSolution, TPopulation, TCandidate>) |
Result |
Gets the result of an algorithm after it has executed.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>) |
Solution |
Gets the result of an algorithm after it has executed.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>) |
Stagnation | Gets or sets the stagnation limit, which is the number of iterations without improvement before declaring stagnation. |
Status |
Gets the AlgorithmStatus following
an execution of the algorithm.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>) |
Throw |
Gets or sets whether to throw an
exception when the algorithm fails to converge.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>) |
Upper |
Gets or sets the upper bounds for the solution.
(Inherited from PopulationBasedOptimizer<TPopulation, TCandidate>) |
Value |
Gets or sets the current value of the objective function.
(Inherited from MultidimensionalOptimizer<T, TReport>) |
Value |
Gets the SimpleConvergenceTest<T> that uses the value of the target functions.
(Inherited from MultidimensionalOptimizer<T, TReport>) |
Weight | Gets or sets the type of dithering applied to the differential weight. |
Methods
Add |
Adds a constraint function g(x) that must satisfy g(x) ≤ 0.
(Inherited from PopulationBasedOptimizer<TSolution, TPopulation, TCandidate>) |
Clear |
Clears all constraint functions.
(Inherited from PopulationBasedOptimizer<TSolution, TPopulation, TCandidate>) |
Equals | Determines whether the specified object is equal to the current object. (Inherited from Object) |
Find |
Searches for an extremum.
(Inherited from MultidimensionalOptimizer<T, TReport>) |
Find |
Searches for a maximum.
(Inherited from MultidimensionalOptimizer<T, TReport>) |
Find |
Searches for a minimum.
(Inherited from MultidimensionalOptimizer<T, TReport>) |
Get | Serves as the default hash function. (Inherited from Object) |
Get | Gets the Type of the current instance. (Inherited from Object) |
ToString | Returns a string that represents the current object. (Inherited from Object) |