Simulated Annealing Optimizer Class
Definition
Assembly: Numerics.NET (in Numerics.NET.dll) Version: 9.1.0
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
Simulated | Constructs a new Simulated Annealing optimizer. |
Simulated | Constructs a new Simulated Annealing optimizer. |
Properties
Best | Gets the best solution found so far. |
Best | Gets the value of the objective function at the best solution. |
Convergence |
Gets the collection of convergence tests for the algorithm.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>) |
Cooling | Gets or sets the rate at which temperature decreases. |
Dimensions |
Gets or sets the number of dimensions of the optimization problem.
(Inherited from MultidimensionalOptimizer) |
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>) |
Evaluations |
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>) |
Extremum |
Gets or sets the type of extremum.
(Inherited from MultidimensionalOptimizer<T, TReport>) |
Fast |
Gets or sets the function that computes the gradient of the objective funciton.
(Inherited from MultidimensionalOptimizer) |
Gradient |
Gets the number of evaluations of the gradient of the objective function.
(Inherited from MultidimensionalOptimizer) |
Gradient |
Gets or sets the function that computes the gradient of the objective funciton.
(Inherited from MultidimensionalOptimizer) |
Gradient |
Gets the VectorConvergenceTest<T> that uses the gradient of the objective function.
(Inherited from MultidimensionalOptimizer) |
Gradient |
Gets or sets the current value of the gradient.
(Inherited from MultidimensionalOptimizer) |
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) |
Initial | Gets or sets the initial temperature for the annealing process. |
Iterations |
Gets the number of iterations needed by the
algorithm to reach the desired accuracy.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>) |
Iterations | Gets or sets the number of iterations to perform at each temperature level. |
Iterations |
Gets the number of iterations remaining.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>) |
Last |
Gets the last correction to the solution of the system of equations.
(Inherited from MultidimensionalOptimizer) |
Lower | Gets or sets the vector of lower bounds for the solution. |
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>) |
Min | Gets or sets the minimum temperature at which to stop. |
Neighborhood | Gets or sets the size of the neighborhood for generating new solutions. |
Objective |
Gets or sets the objective function.
(Inherited from MultidimensionalOptimizer) |
Objective |
Gets or sets a function that evaluates the value and gradient
of the objective function.
(Inherited from MultidimensionalOptimizer) |
Parallel |
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>) |
Solution |
Gets the result of an algorithm after it has executed.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>) |
Solution |
Gets the VectorConvergenceTest<T> that uses the approximate solution.
(Inherited from MultidimensionalOptimizer) |
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>) |
Symbolic |
Gets or sets the objective function.
(Inherited from MultidimensionalOptimizer) |
Temperature | Gets the current temperature of the annealing process. |
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. |
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>) |
Methods
Accept | Determines whether to accept a new solution based on the Metropolis criterion. |
Equals | Determines whether the specified object is equal to the current object. (Inherited from Object) |
Evaluate |
Evaluates the objective function.
(Inherited from MultidimensionalOptimizer) |
Evaluate |
Evaluates the objective function and its gradient at the same time.
(Inherited from MultidimensionalOptimizer) |
Evaluate |
Evaluates the gradient.
(Inherited from MultidimensionalOptimizer) |
Finalize | Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (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>) |
Generate | Generates a new candidate solution in the neighborhood of the current solution. |
Get | Serves as the default hash function. (Inherited from Object) |
Get | Gets the Type of the current instance. (Inherited from Object) |
Increment |
Increments the number of evaluations by one.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>) |
Increment |
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>) |
Memberwise | Creates 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()) |
Report |
Records the results of an algorithm in case it fails.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>) |
Report |
Records the results of an algorithm.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>) |
Report |
Records the results of a algorithm that converged successfully.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>) |
Reset |
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( |
Runs the algorithm using the specified parallelization options.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>) |
Set |
Sets the results of an algorithm's execution.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>) |
Set |
Sets the value of the objective function at the extremum to the supplied value.
(Inherited from MultidimensionalOptimizer<T, TReport>) |
Test |
Checks whether the algorithm has converged.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>) |
Thread |
Increments the number of evaluations by one.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>) |
Thread |
Increments the number of evaluations by the specified amount.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>) |
Throw |
Interprets the AlgorithmStatus and
throws the appropriate exception.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>) |
ToString | Returns a string that represents the current object. (Inherited from Object) |
Update | Updates the temperature according to the cooling schedule. |