Defect Report #426

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Submitter: Fred J. Tydeman
Submission Date: 2013-01-07
Source: WG 14
Reference Document: N1670
Version: 1.0
Date: April 2013
Subject: G.5.1: -yv and -x/v are ambiguous

Summary

The tables in G.5.1 have the mathematical formulas -yv and -x/v. I believe that they are ambiguous as they could have two meanings:

I believe it matters for at least these cases:

  1. The two operands are different NaNs, negate flips the sign of a NaN, and the result of * and / depends upon the sign and value of the NaN.
  2. The result is a NaN from non-NaN operands, negate does not flip the sign of a NaN, while both * and / set the sign of the result as the XOR of the signs of the operands.
  3. All operands are non-NaN, the result is inexact and non-NaN, and a rounding that is not symmetric about zero is in effect.

Suggested Technical Corrigendum


Apr 2013 meeting

Committee Discussion


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