LogGamma

java.lang.Object

org.apache.commons.numbers.gamma.LogGamma

public final class LogGamma extends 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:

Constructor Summary

Constructors

Modifier

Constructor

Description

private

LogGamma()

Private constructor.
Method Summary

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 Details
- LogGamma
  
  private LogGamma()
  
  Private constructor.
Method Details
- 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