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package org.apache.commons.math3.util;

import org.apache.commons.math3.exception.MathIllegalArgumentException;


A strategy to pick a pivoting index of an array for doing partitioning.
See Also:
MedianOf3PivotingStrategy
RandomPivotingStrategy
CentralPivotingStrategy
Since:
3.4/**
 * A strategy to pick a pivoting index of an array for doing partitioning.
 * @see MedianOf3PivotingStrategy
 * @see RandomPivotingStrategy
 * @see CentralPivotingStrategy
 * @since 3.4
 */
public interface PivotingStrategyInterface {

    
Find pivot index of the array so that partition and Kth
element selection can be made
Params:
work – data array
begin – index of the first element of the slice
end – index after the last element of the slice
Throws:
MathIllegalArgumentException – when indices exceeds range
Returns:
the index of the pivot element chosen between the
first and the last element of the array slice/**
     * Find pivot index of the array so that partition and K<sup>th</sup>
     * element selection can be made
     * @param work data array
     * @param begin index of the first element of the slice
     * @param end index after the last element of the slice
     * @return the index of the pivot element chosen between the
     * first and the last element of the array slice
     * @throws MathIllegalArgumentException when indices exceeds range
     */
    int pivotIndex(double[] work, int begin, int end)
        throws MathIllegalArgumentException;

}