Package org.apache.commons.math4.util

Class CentralPivotingStrategy

java.lang.Object

org.apache.commons.math4.util.CentralPivotingStrategy

All Implemented Interfaces:

java.io.Serializable, PivotingStrategyInterface

public class CentralPivotingStrategy
extends java.lang.Object
implements PivotingStrategyInterface, java.io.Serializable

A mid point strategy based on the average of begin and end indices.

Since:

3.4

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor	Description
CentralPivotingStrategy()

Method Summary

Modifier and Type	Method	Description
int	pivotIndex(double[] work, int begin, int end)	Find pivot index of the array so that partition and Kth element selection can be made

Methods inherited from class java.lang.Object

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

Constructor Detail

CentralPivotingStrategy

public CentralPivotingStrategy()

Method Detail

pivotIndex

public int pivotIndex(double[] work,
                      int begin,
                      int end)
               throws MathIllegalArgumentException

Find pivot index of the array so that partition and K^th element selection can be made This in particular picks a average of begin and end indices

Specified by:

pivotIndex in interface PivotingStrategyInterface

Parameters:

work - data array

begin - index of the first element of the slice

end - index after the last element of the slice

Returns:

The index corresponding to a simple average of the first and the last element indices of the array slice

Throws:

MathIllegalArgumentException - when indices exceeds range