Class LogGamma


  • public final class LogGamma
    extends java.lang.Object
    Natural logarithm of the absolute value of \( \Gamma(x) \).

    \[ \operatorname{lgamma}(z) = \ln \lvert \Gamma(x) \rvert \]

    This code has been adapted from the Boost c++ implementation <boost/math/special_functions/gamma.hpp>.

    See Also:
    Boost C++ Log Gamma functions
    • Constructor Summary

      Constructors 
      Modifier Constructor Description
      private LogGamma()
      Private constructor.
    • Method Summary

      All Methods Static Methods Concrete Methods 
      Modifier and Type Method Description
      static double value​(double x)
      Computes the function \( \ln \lvert \Gamma(x) \rvert \), the natural logarithm of the absolute value of \( \Gamma(x) \).
      static double value​(double x, int[] sign)
      Computes the function \( \ln \lvert \Gamma(x) \rvert \), the natural logarithm of the absolute value of \( \Gamma(x) \).
      • Methods inherited from class java.lang.Object

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

      • LogGamma

        private LogGamma()
        Private constructor.
    • Method Detail

      • value

        public static double value​(double x)
        Computes the function \( \ln \lvert \Gamma(x) \rvert \), the natural logarithm of the absolute value of \( \Gamma(x) \).
        Parameters:
        x - Argument.
        Returns:
        \( \ln \lvert \Gamma(x) \rvert \), or NaN if x <= 0 and is an integer.
      • value

        public static double value​(double x,
                                   int[] sign)
        Computes the function \( \ln \lvert \Gamma(x) \rvert \), the natural logarithm of the absolute value of \( \Gamma(x) \).

        The sign output is set to 1 if the sign of gamma(x) is positive or zero; otherwise it is set to -1.

        Parameters:
        x - Argument.
        sign - Sign output. If a non-zero length the first index sign[0] is set on output to the sign of gamma(z).
        Returns:
        \( \ln \lvert \Gamma(x) \rvert \), or NaN if x <= 0 and is an integer.
        Since:
        1.1