This issue has been automatically converted from the original issue lists and some formatting may not have been preserved.
Authors: WG14, C Floating Point Group
Date: 2018-03-24
Reference document: N2224
Submitted against: Floating-point TS 18661 (C11 version, 2014-2016)
Status: Fixed
Fixed in: C23
Converted from: n2397.htm
It is possible that a floating-point value, when converted to a one-digit character string, results in odd numbers no matter which way rounding is done. For roundTiesToEven, IEC 60559 specifies that the larger magnitude value be used.
Suggested Technical Corrigendum:
Add the following to TS 18661-1 clause 10.2 Conversions to character sequences:
Add to F.5 Binary-decimal conversion:
NOTE: IEC 60559 specifies that conversion to one-digit character strings using roundTiesToEven when both choices are odd, shall produce the value with the larger magnitude. This can happen with 9.5 whose nearest neighbors are 9.e0 and 1.e1, both of which are odd.
Comment from WG14 on 2019-05-03:
Apr 2018 meeting
The committee, once it understood the three floating values supplied, agreed with the proposed change.
Subsequently, the author supplied revised values making such an understanding easier. The committee as a whole has yet to see the tweaked values presented below as the Proposed Change.
Add the following to TS 18661-1 clause 10.2 Conversions to character sequences:
Add to F.5 Binary-decimal conversion:
NOTE: IEC 60559 specifies that conversion to one-digit character strings using roundTiesToEven when both choices are odd, shall produce the value with the larger magnitude. This can happen with 9.5e2 whose nearest neighbors are 9.e2 and 1.e3, both of which are odd.
Oct 2018 meeting
A new paper N2283 was presented with revised words from those suggested above in private correspondence.
The committee accepts the Suggested Technical Corrigendum from that paper as the Proposed Change to resolve this issue.
Add the following to TS 18661-1 clause 10.2 Conversions to character sequences:
At the end of F.5 Binary-decimal conversion, add:
NOTE IEC 60559 specifies that conversion to one-digit character strings using roundTiesToEven when both choices have an odd least significant digit, shall produce the value with the larger magnitude. For example, this can happen with 9.5e2 whose nearest neighbors are 9.e2 and 1.e3, both of which have a single odd digit in the significand part.