/// <summary>
/// A convenient way to combine the observations of two Stats objects
/// into a new Stats object.
/// </summary>
/// <param name="a">The first operand</param>
/// <param name="b">The second operand</param>
/// <returns></returns>
public static SummaryStatistics operator +(SummaryStatistics a, SummaryStatistics b)
{
SummaryStatistics result = new SummaryStatistics();
result.Add(a);
result.Add(b);
return(result);
}
public override bool Equals(object obj)
{
if (!base.Equals(obj))
{
return(false);
}
SummaryStatistics s = obj as SummaryStatistics;
if (s == null)
{
return(false);
}
return(s._m3 == _m3 && s._m4 == _m4);
}
/// <summary>
/// Adds a stats object with another type of stats object. The result
/// should be equivalent, up to the effects of numerical imprecision,
/// as if in addition to all the values this object has seen, it has
/// also seen the values added to the other object.
/// </summary>
/// <param name="s"></param>
public void Add(SummaryStatistics s)
{
double delta = s.Mean - Mean;
double na = Count;
double nb = s.Count;
double nx = na + nb;
if (nb == 0.0)
{
return; // No-op.
}
_m4 += s._m4 + delta *
(delta * (delta * delta * na * nb * (na * na - na * nb + nb * nb) / nx +
6 * (na * na * s.M2 + nb * nb * M2)) / nx +
4 * (na * s._m3 - nb * _m3)) / nx;
_m3 += s._m3 + delta * (delta * delta * na * nb * (na - nb) / nx + 3 * (na * s.M2 - nb * M2)) / nx;
base.Add(s);
}