public static int GetRandomTriangularFavoredIndex(int length)
{
if (length > Triangular.MaxInt32)
{
throw new ArgumentOutOfRangeException(nameof(length), length, $"Exceeds maximum Int32 value of {Triangular.MaxInt32}.");
}
var possibilities = (int)Triangular.Forward(length);
var selected = RandomUtilities.Random.Next(possibilities);
var r = Triangular.Reverse(selected);
Debug.Assert(r < length);
return(r);
}