org.apache.flink.api.java.summarize.aggregation

Class CompensatedSum

java.lang.Object

org.apache.flink.api.java.summarize.aggregation.CompensatedSum

All Implemented Interfaces:

Serializable

@Internal
public class CompensatedSum
extends Object
implements Serializable

Used to calculate sums using the Kahan summation algorithm.

The Kahan summation algorithm (also known as compensated summation) reduces the numerical errors that occur when adding a sequence of finite precision floating point numbers. Numerical errors arise due to truncation and rounding. These errors can lead to numerical instability.

See Also:

Kahan Summation Algorithm, Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
static CompensatedSum	ZERO

Constructor Summary

Constructors

Constructor and Description
CompensatedSum(double value, double delta) Used to calculate sums using the Kahan summation algorithm.

Method Summary

Modifier and Type	Method and Description
CompensatedSum	add(CompensatedSum other) Increments the Kahan sum by adding two sums, and updating the correction term for reducing numeric errors.
CompensatedSum	add(double value) Increments the Kahan sum by adding a value without a correction term.
CompensatedSum	add(double value, double delta) Increments the Kahan sum by adding a value and a correction term.
double	delta() The correction term.
double	value() The value of the sum.

Methods inherited from class java.lang.Object

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

Field Detail

ZERO

public static final CompensatedSum ZERO

Constructor Detail

CompensatedSum

public CompensatedSum(double value,
                      double delta)

Used to calculate sums using the Kahan summation algorithm.

Parameters:

value - the sum

delta - correction term

Method Detail

value

public double value()

The value of the sum.

delta

public double delta()

The correction term.

add

public CompensatedSum add(double value,
                          double delta)

Increments the Kahan sum by adding a value and a correction term.

add

public CompensatedSum add(double value)

Increments the Kahan sum by adding a value without a correction term.

add

public CompensatedSum add(CompensatedSum other)

Increments the Kahan sum by adding two sums, and updating the correction term for reducing numeric errors.