org.apache.derby.impl.sql.execute

Class StdDevPAggregator<V extends java.lang.Number>

java.lang.Object

org.apache.derby.impl.sql.execute.VarPAggregator<V>

org.apache.derby.impl.sql.execute.StdDevPAggregator<V>

All Implemented Interfaces:

java.io.Externalizable, java.io.Serializable, Aggregator<V,java.lang.Double,VarPAggregator<V>>

public class StdDevPAggregator<V extends java.lang.Number>
extends VarPAggregator<V>

This class implements the SQL Standard STDDEV_POP() aggregator, computing a population's standard deviation. It relies on VarPAggregator to compute the population variance and then applies the textbook definition of standard deviation:

 √var_pop()
 

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.derby.impl.sql.execute.VarPAggregator

VarPAggregator.Sums

Field Summary

Fields

Modifier and Type	Field and Description
private static long	serialVersionUID

Fields inherited from class org.apache.derby.impl.sql.execute.VarPAggregator

count, sums

Constructor Summary

Constructors

Constructor and Description
StdDevPAggregator()

Method Summary

Modifier and Type	Method and Description
java.lang.Double	terminate() Return the result scalar value

Methods inherited from class org.apache.derby.impl.sql.execute.VarPAggregator

accumulate, computeVar, init, merge, readExternal, writeExternal

Methods inherited from class java.lang.Object

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

Field Detail

serialVersionUID

private static final long serialVersionUID

See Also:

Constant Field Values

Constructor Detail

StdDevPAggregator

public StdDevPAggregator()

Method Detail

terminate

public java.lang.Double terminate()

Description copied from interface: Aggregator

Return the result scalar value

Specified by:

terminate in interface Aggregator<V extends java.lang.Number,java.lang.Double,VarPAggregator<V extends java.lang.Number>>

Overrides:

terminate in class VarPAggregator<V extends java.lang.Number>