Research and Advances

A comparison of floating point summation methods


In the June 1970 issue of Communications, Linz [1] proposed a method of pairwise summing of numbers to reduce accumulated roundoff error. Linz compared his method with only a simple recursive summation. The Linz method should have also been compared with a method published in the January 1965 issue by Kahan [2], which is more accurate. This note compares the schemes by Linz and Kahan with the straight recursive summation. Comparisons of accuracy, speed and storage were carried out on an IBM 360/75 with various compiler optimization levels. (Linz' restriction to a binary exponent is not essential to his method.)

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