A new error-free floating-point summation algorithm

Summation is a basic operation in scientific computing; furthermore division-free arithmetic computations can be boiled down to summation. We propose a new summation algorithm, which consists of double-precision floating-point operations and outputs the error-free sums. The computational time is proportional to the condition number of the problem, is low according to both our estimates and extensive experiments, and further decreases for producing faithful rounding of the sum, rather than its error-free value.