DifferentialEvolutionOptimizer Class

Implements the Differential Evolution algorithm for multi-dimensional optimization.

Definition

Namespace: Numerics.NET.Optimization
Assembly: Numerics.NET (in Numerics.NET.dll) Version: 9.1.0
C#
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.

C#
// 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

Properties

ConvergenceTests Gets the collection of convergence tests for the algorithm.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>)
CrossoverRate Gets or sets the crossover rate used in the algorithm.
DifferentialWeight 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>)
DitheringRange Gets or sets the dithering range used when WeightDithering is set to Uniform.
DiversityTest Gets the convergence test that measures population diversity.
(Inherited from PopulationBasedOptimizer<TSolution, TPopulation, TCandidate>)
EstimatedError Gets a value indicating the size of the absolute error of the result.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>)
EvaluationsNeeded 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>)
ExtremumType Gets or sets the type of extremum.
(Inherited from MultidimensionalOptimizer<T, TReport>)
HasSharedDegreeOfParallelism Indicates whether the degree of parallelism is a property that is shared across instances.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>)
InitialGuess Gets or sets the initial value for the iteration.
(Inherited from MultidimensionalOptimizer<T, TReport>)
InitializationType Gets or sets the method used to initialize the population.
(Inherited from PopulationBasedOptimizer<TPopulation, TCandidate>)
IterationsNeeded Gets the number of iterations needed by the algorithm to reach the desired accuracy.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>)
LowerBounds Gets or sets the vector of lower bounds for the solution.
(Inherited from PopulationBasedOptimizer<TPopulation, TCandidate>)
MaxDegreeOfParallelism Gets or sets the maximum degree of parallelism enabled by this instance.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>)
MaxEvaluations Gets or sets the maximum number of evaluations during the calculation.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>)
MaxIterationsGets or sets the maximum number of iterations to use when approximating the roots of the target function.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>)
MinIterations Gets or sets the minimum iterations that have to be performed.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>)
MutationStrategy Gets or sets the mutation strategy used to generate trial vectors.
ObjectiveFunction Gets or sets the objective function.
(Inherited from MultidimensionalOptimizer<T, TReport>)
ParallelOptions 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>)
PopulationConvergenceTest Gets the convergence test that uses the population's coefficient of variation.
(Inherited from PopulationBasedOptimizer<TSolution, TPopulation, TCandidate>)
PopulationMultiplier Gets or sets the population multiplier used to determine the population size.
PopulationSize 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>)
SolutionReport Gets the result of an algorithm after it has executed.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>)
StagnationLimit 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>)
ThrowExceptionOnFailure Gets or sets whether to throw an exception when the algorithm fails to converge.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>)
UpperBounds Gets or sets the upper bounds for the solution.
(Inherited from PopulationBasedOptimizer<TPopulation, TCandidate>)
ValueAtExtremum Gets or sets the current value of the objective function.
(Inherited from MultidimensionalOptimizer<T, TReport>)
ValueTest Gets the SimpleConvergenceTest<T> that uses the value of the target functions.
(Inherited from MultidimensionalOptimizer<T, TReport>)
WeightDithering Gets or sets the type of dithering applied to the differential weight.

Methods

AddConstraint Adds a constraint function g(x) that must satisfy g(x) ≤ 0.
(Inherited from PopulationBasedOptimizer<TSolution, TPopulation, TCandidate>)
ClearConstraints Clears all constraint functions.
(Inherited from PopulationBasedOptimizer<TSolution, TPopulation, TCandidate>)
EqualsDetermines whether the specified object is equal to the current object.
(Inherited from Object)
FindExtremum Searches for an extremum.
(Inherited from MultidimensionalOptimizer<T, TReport>)
FindMaximum Searches for a maximum.
(Inherited from MultidimensionalOptimizer<T, TReport>)
FindMinimum Searches for a minimum.
(Inherited from MultidimensionalOptimizer<T, TReport>)
GetHashCodeServes as the default hash function.
(Inherited from Object)
GetTypeGets the Type of the current instance.
(Inherited from Object)
ToStringReturns a string that represents the current object.
(Inherited from Object)

See Also