Explicitly The program shown in this appendix is the most complicated to appear in these tutorials. The guts of the accumulation algorithm. Can't call these 'accumulate' because it would be ambiguous. The user interface for accumulate.
Bricks just call the dimension specialized versions.
That is handled in subclasses. A specific type of calculation that returns using a ResultHolder. Let the member data destroy itself. A static function that will be run in a thread. Construct with a const ref to an array.