[Cfp-interest 1716] Re: short hex strings

[Jim Thomas]

I like it, except C doesn’t refer to hexadecimal formats. How about

+++++++++++++++
This implementation choice affects numerical values printed with a precision P that is insufficient to represent all values exactly. Implementations with different conventions about the most significant hexadecimal digit will round at different places, affecting the numerical value of the hexadecimal result. Portable code seeking identical numerical results on different platforms should avoid precisions P that require rounding.
+++++++++++++++

- Jim Thomas


> On Jul 22, 2020, at 9:23 PM, David Hough CFP <pcfp at oakapple.net> wrote:
> 
> 
> "295)Binary implementations can choose the hexadecimal digit to the left of the
> decimal-point character so that subsequent digits align to nibble (4-bit) 
> boundaries."
> 
> Action item: Come up with a sentence to add to footnote 295 (as per CFP 
> 1697) to point out the possible numerical differences in output.
> 
> I tried making one sentence, but it got complicated and confusing.
> 
> Suggestion: add these sentences
> 
> This implementation choice affects numerical
> values printed in short hexadecimal formats that can't represent all values 
> exactly.
> Implementations with different conventions about the most significant
> hexadecimal digit will round at different places, affecting the numerical
> value of the hexadecimal result.    Portable code seeking identical results on
> different platforms should avoid such short hexadecimal formats.
> 
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