using System;
namespace Legalsoft.Truffer
{
public class Eulsum
{
private double[] wksp { get; set; }
private int n { get; set; }
private int ncv { get; set; }
public bool cnvgd { get; set; }
private double sum { get; set; }
private double eps { get; set; }
private double lastval { get; set; }
private double lasteps { get; set; }
public Eulsum(int nmax, double epss)
{
this.wksp = new double[nmax];
this.n = 0;
this.ncv = 0;
this.cnvgd = false;
this.sum = 0.0;
this.eps = epss;
this.lastval = 0.0;
}
public double next(double term)
{
if (n + 1 > wksp.Length)
{
throw new Exception("wksp too small in eulsum");
}
if (n == 0)
{
sum = 0.5 * (wksp[n++] = term);
}
else
{
double tmp = wksp[0];
wksp[0] = term;
for (int j = 1; j < n; j++)
{
double dum = wksp[j];
wksp[j] = 0.5 * (wksp[j - 1] + tmp);
tmp = dum;
}
wsp[n] = 0.5*(wksp[n - 1] + tmp);
if (Math.Abs(wksp[n]) <= Math.Abs(wksp[n - 1]))
{ sum += (0.5 * wsp[n++]); } else { sum += wsp[n]; } } laststeps = Math.Abs(sum - lastVal); if ( laststeps <= eps ) { ncv ++ ; } if ( ncv >= 2 ) { cnvgd = true ; } return ( lastval = sum ) ;
}
}
}