Class StdDevPAggregator<V extends java.lang.Number>
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- org.apache.derby.impl.sql.execute.VarPAggregator<V>
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- org.apache.derby.impl.sql.execute.StdDevPAggregator<V>
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- 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
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Nested Class Summary
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Nested classes/interfaces inherited from class org.apache.derby.impl.sql.execute.VarPAggregator
VarPAggregator.Sums
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Field Summary
Fields Modifier and Type Field Description private static long
serialVersionUID
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Fields inherited from class org.apache.derby.impl.sql.execute.VarPAggregator
count, sums
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Constructor Summary
Constructors Constructor Description StdDevPAggregator()
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method 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
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Field Detail
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serialVersionUID
private static final long serialVersionUID
- See Also:
- Constant Field Values
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Method Detail
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terminate
public java.lang.Double terminate()
Description copied from interface:Aggregator
Return the result scalar value- Specified by:
terminate
in interfaceAggregator<V extends java.lang.Number,java.lang.Double,VarPAggregator<V extends java.lang.Number>>
- Overrides:
terminate
in classVarPAggregator<V extends java.lang.Number>
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