Class VarSAggregator<V extends Number>
java.lang.Object
org.apache.derby.impl.sql.execute.VarPAggregator<V>
org.apache.derby.impl.sql.execute.VarSAggregator<V>
- All Implemented Interfaces:
Externalizable
,Serializable
,Aggregator<V,
Double, VarPAggregator<V>>
- Direct Known Subclasses:
StdDevSAggregator
This class implements the SQL Standard VAR_SAMP() aggregator, computing the variance over a sample. It uses the IBM formula described here:
[ sum(xi2) - sum(xi)2/n ]/(n-1) where n is the number of items in the population x1 ... xn are the items in the population
- See Also:
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Nested Class Summary
Nested classes/interfaces inherited from class org.apache.derby.impl.sql.execute.VarPAggregator
VarPAggregator.Sums
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Field Summary
FieldsFields inherited from class org.apache.derby.impl.sql.execute.VarPAggregator
count, sums
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Constructor Summary
Constructors -
Method Summary
Methods inherited from class org.apache.derby.impl.sql.execute.VarPAggregator
accumulate, init, merge, readExternal, terminate, writeExternal
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Field Details
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serialVersionUID
private static final long serialVersionUID- See Also:
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Constructor Details
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VarSAggregator
public VarSAggregator()
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Method Details
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computeVar
- Overrides:
computeVar
in classVarPAggregator<V extends Number>
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