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Re: [PATCH] fortran/69121 -- Make IEEE_SCALB generic


On Fri, Dec 21, 2018 at 08:59:04PM +0200, Janne Blomqvist wrote:
> On Fri, Dec 21, 2018 at 7:59 PM Steve Kargl <
> >
> > D.3853 = *i;
> > __result_foo = scalbnq (c,
> >     (integer(kind=4)) MAX_EXPR <MIN_EXPR <D.3853, 2147483647>,
> > -2147483647>);
> >
> > The range [-32443,32443] is a subset of [-huge(),huge(0)].
> >
> 
> True. I guess the advantage of scalbln* would be to avoid the MAX/MIN_EXPR
> and casting for kind int64.
> 

fdlibm-based libm has 

#define NMAX    65536
#define NMIN    -65536
double
scalbln(double x, long n)
{

        return (scalbn(x, (n > NMAX) ? NMAX : (n < NMIN) ? NMIN : (int)n));
}

A search for glibc's libm locates https://tinyurl.com/ybcy8w4t
which is a bit-twiddling routine.  Not sure it's worth the
effort.  Joseph Myers might have an opinion.

-- 
Steve


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