/// <summary>
/// Provides a running count of how many intervals (years, days, etc.) a Tbool
/// has been true within some sliding window of time. At the end of that sliding
/// window, this function returns the amount of time that has elapsed within the
/// window during which the Tbool was true.
/// </summary>
/// <remarks>
/// Example: For a given Tbool, at any given point in time, for how many days during the
/// previous 3 days is the Tbool true?
///
/// tb = <FTTTFTTTFFFF>
/// tb.SEI(3, TheDay) = <001232223210>
/// </remarks>
public Tnum SlidingElapsedIntervals(Tnum interval, Tnum windowSize)
{
// If a Tbool is eternally true, return windowSize
if (this.IsTrue)
{
return(windowSize);
}
// The number of true intervals in a sliding window of time equals
// the running count as of time1 minus the running count as of time0.
Tnum r = this.RunningElapsedIntervals(interval);
int size = Convert.ToInt32(windowSize.FirstValue.Val) * -1;
// Counts the current inerval
return(r - r.Shift(size, interval));
}
