NewGamePhysics.Mathematics.Gamma Class Reference

Special functions: Gamma functions. More...

List of all members.

Static Public Member Functions
static double	LogFunction (double x)
	Calculates the logarithm of the gamma function ln(G(x)). Evaluated iteratively. Reference: M. Pike, D. Hill, Algorithm 291: Logarithm of the Gamma Function, Communications of the ACM, Vol. 9, #9, 09/1966, page 684. See also: http://mathworld.wolfram.com/LogGammaFunction.html.

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Detailed Description

Special functions: Gamma functions.

Definition at line 13 of file Gamma.cs.

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Member Function Documentation

static double NewGamePhysics.Mathematics.Gamma.LogFunction

(

double

x

)

[static]

Calculates the logarithm of the gamma function ln(G(x)). Evaluated iteratively. Reference: M. Pike, D. Hill, Algorithm 291: Logarithm of the Gamma Function, Communications of the ACM, Vol. 9, #9, 09/1966, page 684. See also: http://mathworld.wolfram.com/LogGammaFunction.html.

Parameters:

x

The argument of the log gamma function. Value range >0.

Returns:

The logarithm of the gamma function at x.

Definition at line 26 of file Gamma.cs.

        {
            if (x <= 0)
            {
                throw new ArgumentOutOfRangeException("x");
            }

            double f;
            double y;
            double z;

            y = x;
            if (x < 7.0)
            {
                f = 1.0;
                z = y;
                while (z < 7.0)
                {
                    f *= z;
                    z += 1.0;
                }

                y = z;
                f = -Math.Log(f);
            }
            else
            {
                f = 0.0;
            }

            z = 1.0 / (y * y);

            double v =
                f + (y - 0.5) * Math.Log(y) - y + 0.918938533204673 +
                (((-0.000595238095238 * z + 0.000793650793651) * z - 0.002777777777778) * z + 0.083333333333333) / y;

            return v;
        }

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The documentation for this class was generated from the following file:

• C:/Users/Andreas Schiffler/Desktop/SVN/NewGamePhysics/NewGamePhysics/Mathematics/Gamma.cs