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Re: PR83750: CSE erf/erfc pair

On 11/5/18 11:27 AM, Joseph Myers wrote:
> On Sun, 4 Nov 2018, Jeff Law wrote:
> 
>> Don't we have a flag specific to honoring nans?  Would that be better to
>> use than flag_unsafe_math_optimizations?  As Uli mentioned, there's
> 
> That's only relevant for the comparison optimization, of course.
> 
> Converting erfc to 1-erf is dubious, since the whole point of erfc is for 
> cases where 1-erf is inaccurate.  (Conversion in the other direction also 
> needs flag_unsafe_math_optimizations.)
> 
Understood.  Thanks for clarifying.  It seems like
unsafe-math-optimization is a better fit than the nan specific flag.

jeff
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