A floating-point technique for extending the available precision : 2nd ed
T.J. Dekker · Centrum Wiskunde & Informatica (CWI), the national research institute for mathematics and computer science in the Netherlands · 1970
A technique is described for expressing multilength floating-point arithmetic in terms of singlelength floating-point arithmetic, i.e. the arithmetic for an available (say: single or double precision) floating-point number system.The basic algorithms are exact addition and multiplication of two singlelength floating-point numbers, delivering the result as a doublelength floating-point number.A straightforward application of the technique yields a set of algorithms for doublelength arithmetic which are given as ALGOL 60 procedures.