**Document:** WG14 N1670

## Possible defect report: G.5.1: -yv and -x/v
are ambiguous

**Submitter:** Fred J. Tydeman (USA)

**Submission Date:** 2013-01-07

**Subject:**Possible defect report:G.5.1: -yv and -x/v are
ambiguous

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:

- (-y)/v and (-x)/v
- -(y/v) and -(x/v)

I believe it matters for at least these cases:

- 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.
- 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.
- All operands are non-NaN, the result is inexact and
non-NaN, and a rounding that is not symmetric about zero is in
effect.