Abstract : A very simple test, introduced by Ziv, allows one to determine if an approximation to the value f (x) of an elementary function at a given point x suffices to return the floating-point number nearest f(x). The same test may be used when implementing floating-point operations with input and output operands of different formats, using arithmetic operators tailored for manipulating operands of the same format. That test depends on a "magic constant" e. We show how to choose that constant e to make the test reliable and efficient. Various cases are considered, depending on the availability of an fma instruction, and on the range of f (x).
https://hal-ens-lyon.archives-ouvertes.fr/ensl-00693317
Contributeur : Jean-Michel Muller <>
Soumis le : lundi 8 juillet 2013 - 10:56:40
Dernière modification le : mardi 24 novembre 2015 - 01:04:24
Document(s) archivé(s) le : mercredi 9 octobre 2013 - 04:20:52
Florent De Dinechin, Christoph Lauter, Jean-Michel Muller, Serge Torres. On Ziv's rounding test. ACM Transactions on Mathematical Software, Association for Computing Machinery, 2013, 39 (4), pp.26. <ensl-00693317v2>
