Class Product

  • All Implemented Interfaces:
    java.io.Serializable, StorelessUnivariateStatistic, UnivariateStatistic, WeightedEvaluation

    public class Product
    extends AbstractStorelessUnivariateStatistic
    implements java.io.Serializable, WeightedEvaluation
    Returns the product of the available values.

    If there are no values in the dataset, or 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:
    $Revision: 1006299 $ $Date: 2010-10-10 16:47:17 +0200 (dim. 10 oct. 2010) $
    See Also:
    Serialized Form
    • Constructor Summary

      Constructors 
      Constructor Description
      Product()
      Create a Product instance
      Product​(Product original)
      Copy constructor, creates a new Product identical to the original
    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      void clear()
      Clears the internal state of the Statistic
      Product copy()
      Returns a copy of the statistic with the same internal state.
      static void copy​(Product source, Product dest)
      Copies source to dest.
      double evaluate​(double[] values, double[] weights)
      Returns the weighted product of the entries in the input array.
      double evaluate​(double[] values, double[] weights, int begin, int length)
      Returns the weighted product of the entries in the specified portion of the input array, or Double.NaN if the designated subarray is empty.
      double evaluate​(double[] values, int begin, int length)
      Returns the product 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 java.lang.Object

        clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait
    • Constructor Detail

      • Product

        public Product()
        Create a Product instance
      • Product

        public Product​(Product original)
        Copy constructor, creates a new Product identical to the original
        Parameters:
        original - the Product instance to copy
    • Method Detail

      • getN

        public long getN()
        Returns the number of values that have been added.
        Specified by:
        getN in interface StorelessUnivariateStatistic
        Returns:
        the number of values.
      • evaluate

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

        Throws IllegalArgumentException if the array is null.

        Specified by:
        evaluate in interface UnivariateStatistic
        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 product of the values or Double.NaN if length = 0
        Throws:
        java.lang.IllegalArgumentException - if the array is null or the array index parameters are not valid
        See Also:
        UnivariateStatistic.evaluate(double[], int, int)
      • evaluate

        public double evaluate​(double[] values,
                               double[] weights,
                               int begin,
                               int length)

        Returns the weighted product of the entries in the specified portion of the input array, or Double.NaN if the designated subarray is empty.

        Throws IllegalArgumentException if any of the following are true:

        • the values array is null
        • the weights array is null
        • the weights array does not have the same length as the values array
        • the weights array contains one or more infinite values
        • the weights array contains one or more NaN values
        • the weights array contains negative values
        • the start and length arguments do not determine a valid array

        Uses the formula,

            weighted product = ∏values[i]weights[i]
         
        that is, the weights are applied as exponents when computing the weighted product.

        Specified by:
        evaluate in interface WeightedEvaluation
        Parameters:
        values - the input array
        weights - the weights array
        begin - index of the first array element to include
        length - the number of elements to include
        Returns:
        the product of the values or Double.NaN if length = 0
        Throws:
        java.lang.IllegalArgumentException - if the parameters are not valid
        Since:
        2.1
      • evaluate

        public double evaluate​(double[] values,
                               double[] weights)

        Returns the weighted product of the entries in the input array.

        Throws IllegalArgumentException if any of the following are true:

        • the values array is null
        • the weights array is null
        • the weights array does not have the same length as the values array
        • the weights array contains one or more infinite values
        • the weights array contains one or more NaN values
        • the weights array contains negative values

        Uses the formula,

            weighted product = ∏values[i]weights[i]
         
        that is, the weights are applied as exponents when computing the weighted product.

        Specified by:
        evaluate in interface WeightedEvaluation
        Parameters:
        values - the input array
        weights - the weights array
        Returns:
        the product of the values or Double.NaN if length = 0
        Throws:
        java.lang.IllegalArgumentException - if the parameters are not valid
        Since:
        2.1
      • copy

        public static void copy​(Product source,
                                Product dest)
        Copies source to dest.

        Neither source nor dest can be null.

        Parameters:
        source - Product to copy
        dest - Product to copy to
        Throws:
        java.lang.NullPointerException - if either source or dest is null