Class Lanczos

    • Constructor Detail

      • Lanczos

        public Lanczos​(double g,
                       int n,
                       int scale)
        Construct a Lanczos approximation instance.

        Recommended settings are

        g = 607.0 / 128.0; n = 15; scale = 30;
        Parameters:
        g - g
        n - n
        scale - precision
      • Lanczos

        public Lanczos()
        Construct a Lanczos approximation instance using default parameters. The default parameters are:
        g = 607.0 / 128.0; n = 15; scale = 30;
    • Method Detail

      • logGammaQuick

        public double logGammaQuick​(double x)
        Compute log-gamma for a positive value x. All operations are in double precision.
        Parameters:
        x - x in double
        Returns:
        lgamma(x) in double
      • logGamma

        public double logGamma​(double x)
        Compute log-gamma for a positive value x. The accuracy of this function is only as good as the precision of double.
        Parameters:
        x - x in double
        Returns:
        lgamma(x) in double
      • logGamma

        public BigDecimal logGamma​(BigDecimal x)
        Compute log-gamma for a positive value x to arbitrary precision.
        Parameters:
        x - x in BigDecimal
        Returns:
        lgamma(x) in BigDecimal