Class GammaRatio

java.lang.Object
org.apache.commons.numbers.gamma.GammaRatio

public final class GammaRatio extends Object
Ratio of Gamma functions.

\[ \frac{\Gamma(a)}{\Gamma(b)} \]

This code has been adapted from:

  • The Boost c++ implementation <boost/math/special_functions/gamma.hpp>.
Since:
1.1
See Also:
  • Constructor Summary

    Constructors
    Modifier
    Constructor
    Description
    private
    Private constructor.
  • Method Summary

    Modifier and Type
    Method
    Description
    static double
    delta(double a, double delta)
    Computes the ratio of gamma functions of a value and an offset value.
    static double
    value(double a, double b)
    Computes the ratio of gamma functions of two values.

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
  • Constructor Details

    • GammaRatio

      private GammaRatio()
      Private constructor.
  • Method Details

    • value

      public static double value(double a, double b)
      Computes the ratio of gamma functions of two values.

      \[ \frac{\Gamma(a)}{\Gamma(b)} \]

      If either argument is <= 0 or infinite then the result is NaN.

      Parameters:
      a - Argument a (must be positive finite).
      b - Argument b (must be positive finite).
      Returns:
      \( \Gamma(a) / \Gamma(b) \)
    • delta

      public static double delta(double a, double delta)
      Computes the ratio of gamma functions of a value and an offset value.

      \[ \frac{\Gamma(a)}{\Gamma(a + delta)} \]

      Note that the result is calculated accurately even when delta is small compared to a: indeed even if a+delta ~ a. The function is typically used when a is large and delta is very small.

      Parameters:
      a - Argument.
      delta - Argument.
      Returns:
      \( \Gamma(a) / \Gamma(a + delta) \)