org.apache.commons.math3.stat.descriptive.summary
Class SumOfSquares

java.lang.Object
  extended by org.apache.commons.math3.stat.descriptive.AbstractUnivariateStatistic
      extended by org.apache.commons.math3.stat.descriptive.AbstractStorelessUnivariateStatistic
          extended by org.apache.commons.math3.stat.descriptive.summary.SumOfSquares
All Implemented Interfaces:
Serializable, StorelessUnivariateStatistic, UnivariateStatistic, MathArrays.Function

public class SumOfSquares
extends AbstractStorelessUnivariateStatistic
implements Serializable

Returns the sum of the squares of the available values.

If there are no values in the dataset, then 0 is returned. If any of the values are NaN, then NaN is returned.

Note that this implementation is not synchronized. If multiple threads access an instance of this class concurrently, and at least one of the threads invokes the increment() or clear() method, it must be synchronized externally.

Version:
$Id: SumOfSquares.java 1416643 2012-12-03 19:37:14Z tn $
See Also:
Serialized Form

Constructor Summary
SumOfSquares()
          Create a SumOfSquares instance
SumOfSquares(SumOfSquares original)
          Copy constructor, creates a new SumOfSquares identical to the original
 
Method Summary
 void clear()
          Clears the internal state of the Statistic
 SumOfSquares copy()
          Returns a copy of the statistic with the same internal state.
static void copy(SumOfSquares source, SumOfSquares dest)
          Copies source to dest.
 double evaluate(double[] values, int begin, int length)
          Returns the sum of the squares of the entries in the specified portion of the input array, or Double.NaN if the designated subarray is empty.
 long getN()
          Returns the number of values that have been added.
 double getResult()
          Returns the current value of the Statistic.
 void increment(double d)
          Updates the internal state of the statistic to reflect the addition of the new value.
 
Methods inherited from class org.apache.commons.math3.stat.descriptive.AbstractStorelessUnivariateStatistic
equals, evaluate, hashCode, incrementAll, incrementAll
 
Methods inherited from class org.apache.commons.math3.stat.descriptive.AbstractUnivariateStatistic
evaluate, getData, getDataRef, setData, setData, test, test, test, test
 
Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

SumOfSquares

public SumOfSquares()
Create a SumOfSquares instance


SumOfSquares

public SumOfSquares(SumOfSquares original)
             throws NullArgumentException
Copy constructor, creates a new SumOfSquares identical to the original

Parameters:
original - the SumOfSquares instance to copy
Throws:
NullArgumentException - if original is null
Method Detail

increment

public void increment(double d)
Updates the internal state of the statistic to reflect the addition of the new value.

Specified by:
increment in interface StorelessUnivariateStatistic
Specified by:
increment in class AbstractStorelessUnivariateStatistic
Parameters:
d - the new value.

getResult

public double getResult()
Returns the current value of the Statistic.

Specified by:
getResult in interface StorelessUnivariateStatistic
Specified by:
getResult in class AbstractStorelessUnivariateStatistic
Returns:
value of the statistic, Double.NaN if it has been cleared or just instantiated.

getN

public long getN()
Returns the number of values that have been added.

Specified by:
getN in interface StorelessUnivariateStatistic
Returns:
the number of values.

clear

public void clear()
Clears the internal state of the Statistic

Specified by:
clear in interface StorelessUnivariateStatistic
Specified by:
clear in class AbstractStorelessUnivariateStatistic

evaluate

public double evaluate(double[] values,
                       int begin,
                       int length)
                throws MathIllegalArgumentException
Returns the sum of the squares of the entries in the specified portion of the input array, or Double.NaN if the designated subarray is empty.

Throws MathIllegalArgumentException if the array is null.

Specified by:
evaluate in interface UnivariateStatistic
Specified by:
evaluate in interface MathArrays.Function
Overrides:
evaluate in class AbstractStorelessUnivariateStatistic
Parameters:
values - the input array
begin - index of the first array element to include
length - the number of elements to include
Returns:
the sum of the squares of the values or 0 if length = 0
Throws:
MathIllegalArgumentException - if the array is null or the array index parameters are not valid
See Also:
UnivariateStatistic.evaluate(double[], int, int)

copy

public SumOfSquares copy()
Returns a copy of the statistic with the same internal state.

Specified by:
copy in interface StorelessUnivariateStatistic
Specified by:
copy in interface UnivariateStatistic
Specified by:
copy in class AbstractStorelessUnivariateStatistic
Returns:
a copy of the statistic

copy

public static void copy(SumOfSquares source,
                        SumOfSquares dest)
                 throws NullArgumentException
Copies source to dest.

Neither source nor dest can be null.

Parameters:
source - SumOfSquares to copy
dest - SumOfSquares to copy to
Throws:
NullArgumentException - if either source or dest is null


Copyright © 2003-2012 The Apache Software Foundation. All Rights Reserved.