Complex sentence: In a practical implementation, the right-hand-side and initial approximation for the iterations is preprocessed so that all forces inside the subdomains are zero, by one application of the interior correction as above.
Split into simpler sentences: In a practical implementation, the right-hand-side and the initial approximation for the iterations are preprocessed so that all forces inside the subdomains are zero. This is done by one application of the interior correction as above.