org.matheclipse.core.stat.descriptive

Class SymbolicGeometricMean

java.lang.Object

org.matheclipse.core.stat.descriptive.AbstractSymbolicStorelessUnivariateStatistic

org.matheclipse.core.stat.descriptive.SymbolicGeometricMean

All Implemented Interfaces:

java.io.Serializable, StorelessSymbolicUnivariateStatistic, SymbolicUnivariateStatistic

public class SymbolicGeometricMean
extends AbstractSymbolicStorelessUnivariateStatistic
implements java.io.Serializable

Returns the geometric mean of the available values.

Uses a SumOfLogs instance to compute sum of logs and returns exp( 1/n (sum of logs) ). Therefore,

• If any of values are < 0, the result is NaN.
• If all values are non-negative and less than Double.POSITIVE_INFINITY, but at least one value is 0, the result is 0.
• If both Double.POSITIVE_INFINITY and Double.NEGATIVE_INFINITY are among the values, the result is NaN.

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.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
SymbolicGeometricMean() Create a GeometricMean instance
SymbolicGeometricMean(SymbolicSumOfLogs sumOfLogs) Create a GeometricMean instance using the given SumOfLogs instance

Method Summary

Modifier and Type	Method and Description
void	clear() Clears the internal state of the Statistic
IExpr	evaluate(IAST values, int begin, int length) Returns the geometric mean of the entries in the specified portion of the input array.
long	getN() Returns the number of values that have been added.
IExpr	getResult() Returns the current value of the Statistic.
AbstractSymbolicStorelessUnivariateStatistic	getSumLogImpl() Returns the currently configured sum of logs implementation
void	increment(IExpr d) Updates the internal state of the statistic to reflect the addition of the new value.
void	setSumLogImpl(AbstractSymbolicStorelessUnivariateStatistic sumLogImpl) Sets the implementation for the sum of logs.

Methods inherited from class org.matheclipse.core.stat.descriptive.AbstractSymbolicStorelessUnivariateStatistic

evaluate, incrementAll, incrementAll

Methods inherited from class java.lang.Object

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

Constructor Detail

SymbolicGeometricMean

public SymbolicGeometricMean()

Create a GeometricMean instance

SymbolicGeometricMean

public SymbolicGeometricMean(SymbolicSumOfLogs sumOfLogs)

Create a GeometricMean instance using the given SumOfLogs instance

Parameters:

sumOfLogs - sum of logs instance to use for computation

Method Detail

increment

public void increment(IExpr d)

Updates the internal state of the statistic to reflect the addition of the new value.

Specified by:

increment in interface StorelessSymbolicUnivariateStatistic

Specified by:

increment in class AbstractSymbolicStorelessUnivariateStatistic

Parameters:

d - the new value.

getResult

public IExpr getResult()

Returns the current value of the Statistic.

Specified by:

getResult in interface StorelessSymbolicUnivariateStatistic

Specified by:

getResult in class AbstractSymbolicStorelessUnivariateStatistic

Returns:

value of the statistic, Double.NaN if it has been cleared or just instantiated.

clear

public void clear()

Clears the internal state of the Statistic

Specified by:

clear in interface StorelessSymbolicUnivariateStatistic

Specified by:

clear in class AbstractSymbolicStorelessUnivariateStatistic

evaluate

public IExpr evaluate(IAST values,
                      int begin,
                      int length)

Returns the geometric mean of the entries in the specified portion of the input array.

See SymbolicGeometricMean for details on the computing algorithm.

Throws IllegalArgumentException if the array is null.

Specified by:

evaluate in interface SymbolicUnivariateStatistic

Overrides:

evaluate in class AbstractSymbolicStorelessUnivariateStatistic

Parameters:

values - input array containing the values

begin - first array element to include

length - the number of elements to include

Returns:

the geometric mean or Double.NaN if length = 0 or any of the values are <= 0.

Throws:

java.lang.IllegalArgumentException - if the input array is null or the array index parameters are not valid

See Also:

UnivariateStatistic.evaluate(double[], int, int)

getN

public long getN()

Returns the number of values that have been added.

Specified by:

getN in interface StorelessSymbolicUnivariateStatistic

Specified by:

getN in class AbstractSymbolicStorelessUnivariateStatistic

Returns:

the number of values.

setSumLogImpl

public void setSumLogImpl(AbstractSymbolicStorelessUnivariateStatistic sumLogImpl)

Sets the implementation for the sum of logs.

This method must be activated before any data has been added - i.e., before increment has been used to add data; otherwise an IllegalStateException will be thrown.

Parameters:

sumLogImpl - the StorelessUnivariateStatistic instance to use for computing the log sum

Throws:

java.lang.IllegalStateException - if data has already been added (i.e if n > 0)

getSumLogImpl

public AbstractSymbolicStorelessUnivariateStatistic getSumLogImpl()

Returns the currently configured sum of logs implementation

Returns:

the StorelessUnivariateStatistic implementing the log sum