using System;

namespace BrazilTimestampReconstruction
{
	/// <summary>
	/// Returns the value ln[\Gamma(xx)] for xx > 0.
	/// </summary>
	public class Gammln
	{
		public Gammln()
		{
		}
		public double gammln(double xx)
		{
	        double x,y,tmp,ser;
            double[]  cof = new Double[6];
			cof[0] = 76.18009172947146;
			cof[1] = -86.50532032941677;
			cof[2] = 24.01409824083091;
			cof[3] = -1.231739572450155; 
			cof[4] = 0.1208650973866179e-2;
			cof[5] = -0.5395239384953e-5;
            int j;
            y=x=xx;
            tmp=x+5.5;
            tmp -= (x+0.5)*Math.Log(tmp);
            ser=1.000000000190015;
            for (j=0;j<=5;j++) ser += cof[j]/++y;
            return -tmp+Math.Log(2.5066282746310005*ser/x);
		}
	}
}
/*      
        private void button1_Click(object sender, System.EventArgs e)
		{
			NR.SpecialFunctions.Gammln obj = new NR.SpecialFunctions.Gammln();
			textBox1.Text += Convert.ToString(obj.gammln(12.0));
		}
// result
17.5023078458753
*/