MovingAverage.cs

public static unsafe IEnumerable<double> MovingAverage(IList<double> list, int period)
{
    double* doubles = stackalloc double[period];
    double fraction = 1.0 / period;
    double sum = 0;
    for (int i = 0; i < period; i++)
    {
        double @double = list[i] * fraction;
        doubles[i] = @double;
        sum += @double;
    }
    yield return sum;
    int j = period;
    int index = 0;
    while (j < list.Count)
    {
        double old = doubles[index];
        sum -= old;
        double @new = list[j] * fraction;
        doubles[index] = @new;
        sum += @new;
        yield return sum;
        j++;
        index++;
        if (index == period)
            index = 0;
    }
}