Editing Divide-and-conquer algorithm (section)

=== Roundoff control ===
In computations with rounded arithmetic, e.g. with [[floating-point]] numbers, a divide-and-conquer algorithm may yield more accurate results than a superficially equivalent iterative method. For example, one can add ''N'' numbers either by a simple loop that adds each datum to a single variable, or by a D&C algorithm called [[pairwise summation]] that breaks the data set into two halves, recursively computes the sum of each half, and then adds the two sums.  While the second method performs the same number of additions as the first and pays the overhead of the recursive calls, it is usually more accurate.<ref>Nicholas J. Higham, "[https://pdfs.semanticscholar.org/5c17/9d447a27c40a54b2bf8b1b2d6819e63c1a69.pdf The accuracy of floating-point summation]", ''SIAM J. Scientific Computing'' '''14''' (4), 783–799 (1993).</ref>