SimulatedAnnealingOptimizer Class

Represents an optimizer that uses the Simulated Annealing algorithm.

Definition

Namespace: Numerics.NET.Optimization
Assembly: Numerics.NET (in Numerics.NET.dll) Version: 9.1.0
C#
public class SimulatedAnnealingOptimizer : MultidimensionalOptimizer
Inheritance
Object  →  ManagedIterativeAlgorithm<Vector<Double>, Double, OptimizationSolutionReport>  →  MultidimensionalOptimizer<Vector<Double>, OptimizationSolutionReport>  →  MultidimensionalOptimizer  →  SimulatedAnnealingOptimizer

Remarks

Use the SimulatedAnnealingOptimizer to find the global minimum of a multidimensional function. This optimizer is particularly useful for problems where the search space is large and complex, and traditional gradient-based methods are not effective due to the presence of many local minima.

Simulated Annealing is a powerful probabilistic optimization technique inspired by the physical process of annealing in metallurgy, where controlled cooling of metal leads to optimal crystal structures. The algorithm mimics this process by gradually reducing the probability of accepting worse solutions as it "cools down", allowing it to escape local optima while eventually converging to a good solution.

The behavior of the algorithm is controlled through several interacting parameters which you can set in the constructor or directly by changing optimizer properties: The initial temperature and cooling rate determine the exploration phase, while the neighborhood size and iterations per temperature level control local search intensity. As the temperature decreases according to the cooling schedule, the algorithm transitions from broad exploration to focused exploitation.

At high temperatures, the algorithm freely explores the solution space by accepting most moves, even those that temporarily worsen the objective value. The neighborhood size scales with temperature, allowing larger jumps early in the search. As the temperature drops, the acceptance probability for worse solutions decreases, and the neighborhood size shrinks, focusing the search on promising regions.

The number of iterations at each temperature level allows thorough exploration of the current neighborhood before cooling continues. The cooling rate controls how quickly the temperature drops - a slower cooling rate (closer to 1) provides more opportunities to escape local optima but requires more computation time. The minimum temperature and stagnation limit serve as stopping criteria, terminating the search when either sufficient cooling has occurred or no improvements are found for an extended period.

For best results, these parameters should be tuned based on the specific problem:

  • Complex problems with many local optima benefit from higher initial temperatures and slower cooling rates.
  • Larger neighborhood sizes help escape local optima but increase computation time.
  • More iterations per temperature level provide more thorough exploration but slow convergence.
  • The minimum temperature should be set low enough to ensure sufficient convergence.

Constructors

Properties

BestSolution Gets the best solution found so far.
BestValue Gets the value of the objective function at the best solution.
ConvergenceTests Gets the collection of convergence tests for the algorithm.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>)
CoolingRate Gets or sets the rate at which temperature decreases.
Dimensions Gets or sets the number of dimensions of the optimization problem.
(Inherited from MultidimensionalOptimizer)
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>)
EvaluationsRemaining Gets the number of evaluations still available.
(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>)
FastGradientFunction Gets or sets the function that computes the gradient of the objective funciton.
(Inherited from MultidimensionalOptimizer)
GradientEvaluationsNeeded Gets the number of evaluations of the gradient of the objective function.
(Inherited from MultidimensionalOptimizer)
GradientFunction Gets or sets the function that computes the gradient of the objective funciton.
(Inherited from MultidimensionalOptimizer)
GradientTest Gets the VectorConvergenceTest<T> that uses the gradient of the objective function.
(Inherited from MultidimensionalOptimizer)
GradientVector Gets or sets the current value of the gradient.
(Inherited from MultidimensionalOptimizer)
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)
InitialTemperature Gets or sets the initial temperature for the annealing process.
IterationsNeeded Gets the number of iterations needed by the algorithm to reach the desired accuracy.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>)
IterationsPerTemperatureLevel Gets or sets the number of iterations to perform at each temperature level.
IterationsRemaining Gets the number of iterations remaining.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>)
LastCorrection Gets the last correction to the solution of the system of equations.
(Inherited from MultidimensionalOptimizer)
LowerBounds Gets or sets the vector of lower bounds for the solution.
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>)
MinTemperature Gets or sets the minimum temperature at which to stop.
NeighborhoodSize Gets or sets the size of the neighborhood for generating new solutions.
ObjectiveFunction Gets or sets the objective function.
(Inherited from MultidimensionalOptimizer)
ObjectiveFunctionWithGradient Gets or sets a function that evaluates the value and gradient of the objective function.
(Inherited from MultidimensionalOptimizer)
ParallelOptions Gets or sets the configuration for the parallel behavior of the algorithm.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>)
Random Gets or sets the random number generator used for generating random perturbations and acceptance probabilities.
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>)
SolutionTest Gets the VectorConvergenceTest<T> that uses the approximate solution.
(Inherited from MultidimensionalOptimizer)
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>)
SymbolicObjectiveFunction Gets or sets the objective function.
(Inherited from MultidimensionalOptimizer)
Temperature Gets the current temperature of the annealing process.
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.
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>)

Methods

AcceptNewSolution Determines whether to accept a new solution based on the Metropolis criterion.
EqualsDetermines whether the specified object is equal to the current object.
(Inherited from Object)
Evaluate Evaluates the objective function.
(Inherited from MultidimensionalOptimizer)
EvaluateFunctionAndGradient Evaluates the objective function and its gradient at the same time.
(Inherited from MultidimensionalOptimizer)
EvaluateGradient Evaluates the gradient.
(Inherited from MultidimensionalOptimizer)
FinalizeAllows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection.
(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>)
GenerateNeighbor Generates a new candidate solution in the neighborhood of the current solution.
GetHashCodeServes as the default hash function.
(Inherited from Object)
GetTypeGets the Type of the current instance.
(Inherited from Object)
IncrementEvaluations() Increments the number of evaluations by one.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>)
IncrementEvaluations(Int32) Increments the number of evaluations by the specified amount.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>)
Iterate Performs one iteration of the algorithm.
(Overrides ManagedIterativeAlgorithm<T, TError, TReport>.Iterate())
Iterated Performs tasks after the iteration is completed, but before the status of the algorithm is finalized.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>)
MemberwiseCloneCreates a shallow copy of the current Object.
(Inherited from Object)
OnConvergence Performs any tasks after the main algorithm has converged.
(Inherited from MultidimensionalOptimizer)
OnFailure Performs any tasks after the main algorithm has failed to converge.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>)
OnInit Performs initialization before the first iteration.
(Overrides MultidimensionalOptimizer.OnInit())
ReportFailure Records the results of an algorithm in case it fails.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>)
ReportResult Records the results of an algorithm.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>)
ReportSuccess Records the results of a algorithm that converged successfully.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>)
ResetEvaluations Resets the number of evaluations to zero.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>)
Restart Prepares the algorithm to be run again with possibly different inputs.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>)
Run() Runs the algorithm.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>)
Run(ParallelOptions) Runs the algorithm using the specified parallelization options.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>)
SetResult Sets the results of an algorithm's execution.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>)
SetValueAtExtremum Sets the value of the objective function at the extremum to the supplied value.
(Inherited from MultidimensionalOptimizer<T, TReport>)
TestConvergence Checks whether the algorithm has converged.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>)
ThreadSafeIncrementEvaluations() Increments the number of evaluations by one.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>)
ThreadSafeIncrementEvaluations(Int32) Increments the number of evaluations by the specified amount.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>)
ThrowConvergenceException Interprets the AlgorithmStatus and throws the appropriate exception.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>)
ToStringReturns a string that represents the current object.
(Inherited from Object)
UpdateTemperature Updates the temperature according to the cooling schedule.

See Also