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java.lang.Objectorg.apache.commons.math.stat.descriptive.AbstractUnivariateStatistic
org.apache.commons.math.stat.descriptive.AbstractStorelessUnivariateStatistic
org.apache.commons.math.stat.descriptive.moment.FirstMoment
org.apache.commons.math.stat.descriptive.moment.SecondMoment
org.apache.commons.math.stat.descriptive.moment.ThirdMoment
public class ThirdMoment
Computes a statistic related to the Third Central Moment. Specifically, what is computed is the sum of cubed deviations from the sample mean.
The following recursive updating formula is used:
Let
SecondMoment
new value = old value - 3 * (dev/n) * m2 + (n-1) * (n -2) * (dev^3/n^2)
Returns Double.NaN
if no data values have been added and
returns 0
if there is just one value in the data set.
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.
Field Summary | |
---|---|
protected double |
m3
third moment of values that have been added |
protected double |
nDevSq
Square of deviation of most recently added value from previous first moment, normalized by previous sample size. |
private static long |
serialVersionUID
Serializable version identifier |
Fields inherited from class org.apache.commons.math.stat.descriptive.moment.SecondMoment |
---|
m2 |
Fields inherited from class org.apache.commons.math.stat.descriptive.moment.FirstMoment |
---|
dev, m1, n, nDev |
Constructor Summary | |
---|---|
ThirdMoment()
Create a FourthMoment instance |
|
ThirdMoment(ThirdMoment original)
Copy constructor, creates a new ThirdMoment identical
to the original |
Method Summary | |
---|---|
void |
clear()
Clears the internal state of the Statistic |
ThirdMoment |
copy()
Returns a copy of the statistic with the same internal state. |
static void |
copy(ThirdMoment source,
ThirdMoment dest)
Copies source to dest. |
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.math.stat.descriptive.moment.SecondMoment |
---|
copy |
Methods inherited from class org.apache.commons.math.stat.descriptive.moment.FirstMoment |
---|
copy, getN |
Methods inherited from class org.apache.commons.math.stat.descriptive.AbstractStorelessUnivariateStatistic |
---|
equals, evaluate, evaluate, hashCode, incrementAll, incrementAll |
Methods inherited from class org.apache.commons.math.stat.descriptive.AbstractUnivariateStatistic |
---|
test, test |
Methods inherited from class java.lang.Object |
---|
clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait |
Field Detail |
---|
private static final long serialVersionUID
protected double m3
protected double nDevSq
Constructor Detail |
---|
public ThirdMoment()
public ThirdMoment(ThirdMoment original)
ThirdMoment
identical
to the original
original
- the ThirdMoment
instance to copyMethod Detail |
---|
public void increment(double d)
increment
in interface StorelessUnivariateStatistic
increment
in class SecondMoment
d
- the new value.public double getResult()
getResult
in interface StorelessUnivariateStatistic
getResult
in class SecondMoment
Double.NaN
if it
has been cleared or just instantiated.public void clear()
clear
in interface StorelessUnivariateStatistic
clear
in class SecondMoment
public ThirdMoment copy()
copy
in interface StorelessUnivariateStatistic
copy
in interface UnivariateStatistic
copy
in class SecondMoment
public static void copy(ThirdMoment source, ThirdMoment dest)
Neither source nor dest can be null.
source
- ThirdMoment to copydest
- ThirdMoment to copy to
java.lang.NullPointerException
- if either source or dest is null
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