Public Comment Number PC-UK0150 ISO/IEC CD 9899 (SC22N2620) Public Comment =========================================== Date: 1998-02-25 Author: N.M Maclaren Author Affiliation: Self Postal Address: University of Cambridge, Computer Laboratory, New Museums Site, Pembroke Street, Cambridge CB3 3QG, United Kingdom E-mail Address: Telephone Number: +44 1223 334761 Fax Number: +44 1223 334679 Number of individual comments: 1 Comment 1. Category: Normative change to intent of existing feature Committee Draft subsection: 7.7.12.2, 7.7.12.3, F.9.9.2, F.9.9.3 Title: Mathematically incorrect behaviour of fmax/fmin Detailed description: 7.7.12.2 and 7.7.12.3 footnotes 182 and 183 should be scrapped. They are mathematically incorrect, as IEEE 754 uses NaNs as an error indicator and NOT a missing value indicator, and are an unreasonable restriction on non-IEEE implementations. The specification of these in F.9.9.2 and F.9.9.3 is mathematically incompatible with IEEE 754's use of NaNs. Furthermore, the example code given does not raise the invalid exception if an argument is a NaN. The combination of these provides a very serious impact on robustness. I suggest changing the wording to: 1 - If either argument is a NaN then fmax returns one of its argument NaNs; it is unspecified whether the invalid exception will be raised. The body of the fmax function might be { return (isgreaterequal(x,y) ? x : y); } 7.8.2 Complex functions ==== Comment numeric-28 ====