Class IntSumOfSquares
- All Implemented Interfaces:
DoubleSupplier
,IntConsumer
,IntSupplier
,LongSupplier
,IntStatistic
,StatisticAccumulator<IntSumOfSquares>
,StatisticResult
\[ \sum_{i=1}^n x_i^2 \]
where \( n \) is the number of samples.
- The result is zero if no values are observed.
The implementation uses an exact integer sum to compute the sum of squared values.
The exact sum is returned using getAsBigInteger()
. Methods that return int
or
long
primitives will raise an exception if the result overflows.
Note that the implementation does not use BigInteger
arithmetic; for
performance the sum is computed using primitives to create an unsigned 128-bit integer.
Support is provided for at least 263 observations.
This class is designed to work with (though does not require) streams.
This implementation is not thread safe.
If multiple threads access an instance of this class concurrently,
and at least one of the threads invokes the accept
or
combine
method, it must be synchronized externally.
However, it is safe to use accept
and combine
as accumulator
and combiner
functions of
Collector
on a parallel stream,
because the parallel implementation of Stream.collect()
provides the necessary partitioning, isolation, and merging of results for
safe and efficient parallel execution.
- Since:
- 1.1
-
Field Summary
FieldsModifier and TypeFieldDescriptionprivate static final int
Small array sample size.private final UInt128
Sum of the squared values. -
Constructor Summary
ConstructorsModifierConstructorDescriptionprivate
Create an instance.private
IntSumOfSquares
(UInt128 sumSq) Create an instance. -
Method Summary
Modifier and TypeMethodDescriptionvoid
accept
(int value) Updates the state of the statistic to reflect the addition ofvalue
.combine
(IntSumOfSquares other) Combines the state of theother
statistic into this one.static IntSumOfSquares
create()
Creates an instance.Gets the sum of squares of all input values.double
Gets the sum of squares of all input values.int
getAsInt()
Gets the sum of squares of all input values.long
Gets the sum of squares of all input values.(package private) UInt128
Gets the sum of squares.static IntSumOfSquares
of
(int... values) Returns an instance populated using the inputvalues
.Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
Methods inherited from interface java.util.function.IntConsumer
andThen
-
Field Details
-
SMALL_SAMPLE
private static final int SMALL_SAMPLESmall array sample size. Used to avoid computing with UInt96 then converting to UInt128.- See Also:
-
sumSq
Sum of the squared values.
-
-
Constructor Details
-
IntSumOfSquares
private IntSumOfSquares()Create an instance. -
IntSumOfSquares
Create an instance.- Parameters:
sumSq
- Sum of the squared values.
-
-
Method Details
-
create
Creates an instance.The initial result is zero.
- Returns:
IntSumOfSquares
instance.
-
of
Returns an instance populated using the inputvalues
.- Parameters:
values
- Values.- Returns:
IntSumOfSquares
instance.
-
getSumOfSquares
UInt128 getSumOfSquares()Gets the sum of squares.This is package private for use in
IntStatistics
.- Returns:
- the sum of squares
-
accept
public void accept(int value) Updates the state of the statistic to reflect the addition ofvalue
.- Specified by:
accept
in interfaceIntConsumer
- Parameters:
value
- Value.
-
getAsInt
public int getAsInt()Gets the sum of squares of all input values.When no values have been added, the result is zero.
Warning: This will raise an
ArithmeticException
if the result is not within the range[0, 2^31)
.- Specified by:
getAsInt
in interfaceIntSupplier
- Specified by:
getAsInt
in interfaceStatisticResult
- Returns:
- sum of all values.
- Throws:
ArithmeticException
- if theresult
overflows anint
- See Also:
-
getAsLong
public long getAsLong()Gets the sum of squares of all input values.When no values have been added, the result is zero.
Warning: This will raise an
ArithmeticException
if the result is not within the range[0, 2^63)
.- Specified by:
getAsLong
in interfaceLongSupplier
- Specified by:
getAsLong
in interfaceStatisticResult
- Returns:
- sum of all values.
- Throws:
ArithmeticException
- if theresult
overflows along
- See Also:
-
getAsDouble
public double getAsDouble()Gets the sum of squares of all input values.When no values have been added, the result is zero.
Note that this conversion can lose information about the precision of the
BigInteger
value.- Specified by:
getAsDouble
in interfaceDoubleSupplier
- Returns:
- sum of squares of all values.
- See Also:
-
getAsBigInteger
Gets the sum of squares of all input values.When no values have been added, the result is zero.
- Specified by:
getAsBigInteger
in interfaceStatisticResult
- Returns:
- sum of squares of all values.
-
combine
Description copied from interface:StatisticAccumulator
Combines the state of theother
statistic into this one.- Specified by:
combine
in interfaceStatisticAccumulator<IntSumOfSquares>
- Parameters:
other
- Another statistic to be combined.- Returns:
this
instance after combiningother
.
-