Exactly Rounded Sums, Means and Dot Products

Sums of double-precision numbers computed exactly and rounded once, so the result is the correctly rounded true sum and does not depend on the order of the elements, the platform, or whether R was built with long doubles. Built on the small and large superaccumulators of Neal (2015) . Provides exactly rounded sums, means, cumulative sums, dot products and norms, row, column and grouped sums, accumulators that can be built in pieces and merged across processes, and a registered 'C' interface for other packages.