CrossoverDoubleBLX

java.lang.Object
- org.opt4j.operator.crossover.CrossoverDouble
- - org.opt4j.operator.crossover.CrossoverDoubleElementwise
  - - org.opt4j.operator.crossover.CrossoverDoubleBLX

All Implemented Interfaces:

Operator<DoubleGenotype>, Crossover<DoubleGenotype>
```
public class CrossoverDoubleBLX
extends CrossoverDoubleElementwise
```
The CrossoverDoubleBLX is an implementation of the blend crossover operator proposed by Eshelman and Schaffer, 1993.
The BLX crossover is applied element-wise. For two double values y and x (assuming y > x one offspring value is created in the uniform interval [x-(y-x)*alpha;y+(y-x)*alpha].

If alpha is set to 0, the operator creates a random solution between x and y. Values greater zero allow offspring that is apart from the interval between x and y. The authors report best performance with alpha = 0.5 which is then called the BLX-0.5 operator.

Field Summary

Fields
Modifier and Type Field Description

protected double alpha
- Fields inherited from class org.opt4j.operator.crossover.CrossoverDouble
  normalize, random

Constructor Summary

Constructors
Constructor	Description
`CrossoverDoubleBLX(double alpha, NormalizeDouble normalize, Rand random)`	Constructs a `CrossoverDoubleBLX` with an alpha value, an `NormalizeDouble` operator, and a random number generator.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`Pair<Double>`	`crossover(double x, double y)`	Performs a crossover with two double values.
`protected double`	`next(double lo, double hi)`	Calculates a random value in the interval `[lo-(hi-lo)alpha;hi+(hi-lo)alpha]`.

Methods inherited from class org.opt4j.operator.crossover.CrossoverDoubleElementwise
crossover

Methods inherited from class org.opt4j.operator.crossover.CrossoverDouble
crossover

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - alpha
```
protected final double alpha
```
- Constructor Detail
  - CrossoverDoubleBLX
```
@Inject
public CrossoverDoubleBLX(double alpha,
                          NormalizeDouble normalize,
                          Rand random)
```
    Constructs a CrossoverDoubleBLX with an alpha value, an NormalizeDouble operator, and a random number generator.
    
    Parameters:
    
    alpha - the alpha value
    
    normalize - the normalize operator
    
    random - the random number generator
- Method Detail
  - crossover
```
public Pair<Double> crossover(double x,
                              double y)
```
    Description copied from class: CrossoverDoubleElementwise
    
    Performs a crossover with two double values.
    
    Specified by:
    
    crossover in class CrossoverDoubleElementwise
    
    Parameters:
    
    x - the first value
    
    y - the second value
    
    Returns:
    
    the resulting values
  - next
```
protected double next(double lo,
                      double hi)
```
    Calculates a random value in the interval [lo-(hi-lo)*alpha;hi+(hi-lo)*alpha].
    
    Parameters:
    
    lo - the smaller double value
    
    hi - the bigger double value
    
    Returns:
    
    a random value in the interval