Package org.apache.commons.numbers.combinatorics

Class BinomialCoefficientDouble

java.lang.Object
org.apache.commons.numbers.combinatorics.BinomialCoefficientDouble
public final class BinomialCoefficientDouble extends Object
Representation of the binomial coefficient, as a double. It is "n choose k", the number of k-element subsets that can be selected from an n-element set.

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    private static final int
    LIMIT_N_LONG
    The maximum n that can be computed without overflow of a long for any m.
    private static final int
    MAX_FACTORIAL
    The maximum factorial that can be represented as a double.
    private static final int
    MAX_M
    The maximum m that can be computed without overflow of a double.
    private static final int
    SMALL_M
    The maximum m that can be computed without intermediate overflow for any n.
    private static final int
    SMALL_N
    The maximum n that can be computed without intermediate overflow for any m.

  • Constructor Summary

    Constructors
    Modifier
    Constructor
    Description
    private
    BinomialCoefficientDouble()
    Private constructor.

  • Method Summary

    Modifier and Type
    Method
    Description
    static double
    value(int n, int k)
    Computes the binomial coefficient.

    Methods inherited from class java.lang.Object

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

  • Field Details

    • MAX_FACTORIAL

      private static final int MAX_FACTORIAL
      The maximum factorial that can be represented as a double.
      See Also:

    • LIMIT_N_LONG

      private static final int LIMIT_N_LONG
      The maximum n that can be computed without overflow of a long for any m. C(66, 33) < 2^63.
      See Also:

    • MAX_M

      private static final int MAX_M
      The maximum m that can be computed without overflow of a double. C(1030, 515) ~ 2.85e308.
      See Also:

    • SMALL_N

      private static final int SMALL_N
      The maximum n that can be computed without intermediate overflow for any m. C(1020, 510) * 510 ~ 1.43e308.
      See Also:

    • SMALL_M

      private static final int SMALL_M
      The maximum m that can be computed without intermediate overflow for any n. C(2147483647, 37) * 37 ~ 5.13e303.
      See Also:

  • Constructor Details

    • BinomialCoefficientDouble

      private BinomialCoefficientDouble()
      Private constructor.

  • Method Details

    • value

      public static double value(int n, int k)
      Computes the binomial coefficient.

      The largest value of n for which all coefficients can fit into a double is 1029. Larger n may result in infinity depending on the value of k.

      Any min(k, n - k) >= 515 cannot fit into a double and will result in infinity.

      Parameters:
      n - Size of the set.
      k - Size of the subsets to be counted.
      Returns:
      n choose k.
      Throws:
      IllegalArgumentException - if n < 0, k < 0 or k > n.