public static float Fractile(Narray <float> a, double f)
{
Floatarray temp = new Floatarray();
if (!(f >= 0 && f <= 1))
{
throw new Exception("CHECK: f >= 0 && f <= 1");
}
temp.Copy(a);
temp.Reshape(temp.Length1d());
Quicksort(temp);
return(temp[(int)(f * temp.Length())]);
}