BacktrackingLineSearch Class

Represents a line search using a backtracking algorithm.

Definition

Namespace: Numerics.NET.Optimization.LineSearches
Assembly: Numerics.NET (in Numerics.NET.dll) Version: 9.0.3
C#
public sealed class BacktrackingLineSearch : OneDimensionalOptimizer
Inheritance
Object  →  ManagedIterativeAlgorithm<Double, Double, SolutionReport<Double, Double>>  →  ManagedIterativeAlgorithm<Double>  →  OneDimensionalOptimizer  →  BacktrackingLineSearch

Remarks

Use the BacktrackingLineSearch class as a line search method in a multidimensional optimization algorithm. This class is not suitable for general optimization in one dimension.

The backtracking algorithm is the line search method of choice for most applications, particularly when the gradient of the objective function is relatively expensive. The algorithm uses a custom termination criterion based on the Wolfe conditions. These conditions guarantee convergence of quasi-Newton algorithms in most situations.

The algorithm uses the Armijo conditions as termination criteria. The parameter of the Armijo conditions can be set or retrieved through the DescentFactor property, while the rate of backtracking can be controlled through the MinContractionFactor and MaxContractionFactor properties.

Constructors

BacktrackingLineSearch(MultidimensionalOptimizer) Constructs a new BacktrackingLineSearch object.
BacktrackingLineSearch(MultidimensionalOptimizer, Double, Double) Constructs a new BacktrackingLineSearch object.
BacktrackingLineSearch(MultidimensionalOptimizer, Double, Double, Double) Constructs a new BacktrackingLineSearch object.

Properties

ConvergenceTests Gets the collection of convergence tests for the algorithm.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>)
DerivativeOfObjectiveFunction Gets or sets the derivative of the objective function.
(Inherited from OneDimensionalOptimizer)
DescentFactor Gets or sets the factor in the sufficient descent condition.
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 the approximation to the extremum after the algorithm has run.
(Inherited from OneDimensionalOptimizer)
ExtremumType Gets or sets the type of extremum.
(Inherited from OneDimensionalOptimizer)
HasSharedDegreeOfParallelism Indicates whether the degree of parallelism is a property that is shared across instances.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>)
IsBracketValid Gets whether the algorithm's current bracket is valid.
(Inherited from OneDimensionalOptimizer)
IterationsNeeded Gets the number of iterations needed by the algorithm to reach the desired accuracy.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>)
MaxContractionFactor Gets or sets the largest allowed contraction factor between steps in the backtracking procedure.
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>)
MaxStepLength Gets or sets the largest allowed step length.
MinContractionFactor Gets or sets the smallest allowed contraction factor between steps in the backtracking procedure.
MinIterations Gets or sets the minimum iterations that have to be performed.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>)
ObjectiveFunction Gets or sets the objective function.
(Inherited from OneDimensionalOptimizer)
ObjectiveFunctionWithDerivative Gets or sets a function that computes the value of the objective function and its derivative.
(Inherited from OneDimensionalOptimizer)
ParallelOptions Gets or sets the configuration for the parallel behavior of the algorithm.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>)
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 convergence test that uses the solution of the optimization.
(Inherited from OneDimensionalOptimizer)
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 OneDimensionalOptimizer)
ThrowExceptionOnFailure Gets or sets whether to throw an exception when the algorithm fails to converge.
(Inherited from ManagedIterativeAlgorithm<T, TError, TReport>)
ValueAtExtremum Gets the value of the objective function at the approximation to the extremum after the algorithm has run.
(Inherited from OneDimensionalOptimizer)

Methods

EqualsDetermines whether the specified object is equal to the current object.
(Inherited from Object)
FindBracket() Finds an interval that brackets the extremum, starting from the interval [0,1].
(Inherited from OneDimensionalOptimizer)
FindBracket(Double) Finds an interval that brackets the extremum, starting from an interval of unit width centered around the specified point.
(Inherited from OneDimensionalOptimizer)
FindBracket(Double, Double) Finds an interval that brackets the extremum, starting from an interval with the specified bounds.
(Inherited from OneDimensionalOptimizer)
FindBracket(Double, Double, Double) Finds an interval that brackets the extremum, starting from an interval with the specified bounds and interior point.
(Inherited from OneDimensionalOptimizer)
FindExtremum Searches for an extremum.
(Inherited from OneDimensionalOptimizer)
FindMaximum(Func<Double, Double>, Double) Computes a maximum of the specified function.
(Inherited from OneDimensionalOptimizer)
FindMaximum(Func<Double, Double>, Double, Double) Computes a maximum of the specified function.
(Inherited from OneDimensionalOptimizer)
FindMinimum(Func<Double, Double>, Double) Computes a minimum of the specified function.
(Inherited from OneDimensionalOptimizer)
FindMinimum(Func<Double, Double>, Double, Double) Computes a minimum of the specified function.
(Inherited from OneDimensionalOptimizer)
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