x0 + x1 + ... + xn
| InvalidOperationException | any x is signaling NaN | 
| InvalidOperationException | there are two infinite elements with different sign | 
| OverflowException | result is too big to be represented | 
| UnderflowException | result is too small to be represented | 
| InexactException | result is inexact | 
Sums elements of x using a higher precision, rounding only once at the end.</br>