[PATCH 20/25] math: Use tgamma from CORE-MATH

[DJ Delorie]

Paul Zimmermann <Paul.Zimmermann@inria.fr> writes:
> you are right. One could add:
>
> /* split x into a high part xh (return value) and a low part xl,
>    where ulp(xh) = 2^-25. If |x| <= 2^26, the splitting is exact:
>    x = xh + xl */

You know, it took me a long time to grok what this high/low part meant,
as it's not being used the same as a register pair hi-lo.  Both values
are doubles, but their exponents differ by (about) 53, so the mantissas
cover a wider range of significant bits, yes?  This allows the math to
keep more precision by storing it in the "low" double, but there's no
shift-merge like there would be with a register pair.