Package org.apache.commons.statistics.descriptive

Class LongSumOfSquares

  • All Implemented Interfaces:
    DoubleSupplier, IntSupplier, LongConsumer, LongSupplier, LongStatistic, StatisticAccumulator<LongSumOfSquares>, StatisticResult
    public final class LongSumOfSquares
extends Object
implements LongStatistic, StatisticAccumulator<LongSumOfSquares>
    Returns the sum of the squares of the available values. Uses the following definition:

    \[ \sum_{i=1}^n x_i^2 \]

    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 192-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