Package org.apache.commons.math4.legacy.optim.nonlinear.scalar.noderiv

Class Simplex

java.lang.Object

org.apache.commons.math4.legacy.optim.nonlinear.scalar.noderiv.Simplex

All Implemented Interfaces:

OptimizationData

public final class Simplex
extends Object
implements OptimizationData

Represents a simplex.

See Also:

SimplexOptimizer

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static interface	Simplex.TransformFactory	Generator of simplex transform.

Method Summary

Modifier and Type	Method	Description
static Simplex	alongAxes(double[] steps)	The start configuration for simplex is built from a box parallel to the canonical axes of the space.
List<PointValuePair>	asList()	Creates a (deep) copy of the simplex points.
static Simplex	equalSidesAlongAxes(int dim, double sideLength)	Builds simplex with the given side length.
Simplex	evaluate(MultivariateFunction function, Comparator<PointValuePair> comparator)	Evaluates the (non-evaluated) simplex points and returns a new instance with vertices sorted from best to worst.
PointValuePair	get(int index)	Retrieves a copy of the simplex point stored at index.
int	getDimension()	Returns the space dimension.
int	getSize()	Returns the number of vertices.
static Simplex	of(double[][] simplex)	Builds from a given set of coordinates.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

of

public static Simplex of(double[][] simplex)

Builds from a given set of coordinates.

Parameters:

simplex - Simplex coordinates.

Returns:

a new instance.

Throws:

NotStrictlyPositiveException - if the reference simplex does not contain at least one point.

DimensionMismatchException - if there is a dimension mismatch in the reference simplex.

IllegalArgumentException - if one of its vertices is duplicated.

equalSidesAlongAxes

public static Simplex equalSidesAlongAxes(int dim,
                                          double sideLength)

Builds simplex with the given side length.

Parameters:

dim - Space dimensions.

sideLength - Length of the sides of the hypercube.

Returns:

a new instance.

alongAxes

public static Simplex alongAxes(double[] steps)

The start configuration for simplex is built from a box parallel to the canonical axes of the space. The simplex is the subset of vertices of a box parallel to the canonical axes. It is built as the path followed while traveling from one vertex of the box to the diagonally opposite vertex moving only along the box edges. The first vertex of the box will be located at the origin of the coordinate system. To be used for simplex-based optimization, the simplex must be translated so that its first vertex will be the initial guess. For example, in dimension 3 a simplex has 4 vertices. Setting the steps to (1, 10, 2) and the start point to (1, 1, 1) would imply the initial simplex would be:

1. (1, 1, 1),
2. (2, 1, 1),
3. (2, 11, 1),
4. (2, 11, 3).

Parameters:

steps - Steps along the canonical axes representing box edges. They may be negative but not zero.

Returns:

a new instance.

Throws:

ZeroException - if one of the steps is zero.

getDimension

public int getDimension()

Returns the space dimension.

Returns:

the dimension of the simplex.

getSize

public int getSize()

Returns the number of vertices.

Returns:

the size of the simplex.

evaluate

public Simplex evaluate(MultivariateFunction function,
                        Comparator<PointValuePair> comparator)

Evaluates the (non-evaluated) simplex points and returns a new instance with vertices sorted from best to worst.

Parameters:

function - Evaluation function.

comparator - Comparator for sorting vertices, from best to worst.

Returns:

a new instance in which the vertices are sorted according to the given comparator.

get

public PointValuePair get(int index)

Retrieves a copy of the simplex point stored at index.

Parameters:

index - Location.

Returns:

the point at location index.

asList

public List<PointValuePair> asList()

Creates a (deep) copy of the simplex points.

Returns:

the points.