Use of C99 extra long double math functions after r236148
Steve Kargl
sgk at troutmask.apl.washington.edu
Wed Jul 25 17:31:48 UTC 2012
On Wed, Jul 25, 2012 at 12:27:43PM -0500, Stephen Montgomery-Smith wrote:
> On 07/25/12 11:29, Rainer Hurling wrote:
>
> >Many thanks to you three for implementing expl() with r238722 and r238724.
> >
> >I am not a C programmer, but would like to ask if the following example
> >is correct and suituable as a minimalistic test of this new C99 function?
> >
> >
(program deleted)
> >
> >Compiled with 'c99 -o math_expl math_expl.c -lm' and running afterwards
> >it gives me:
> >
> >exp(2.000000) is
> >7.3890560989306504069
> >
> >expl(2.000000) is
> >7.38905609893065022739794
> >
>
> Just as a point of comparison, here is the answer computed using
> Mathematica:
>
> N[Exp[2], 50]
> 7.3890560989306502272304274605750078131803155705518
>
> As you can see, the expl solution has only a few digits more accuracy
> that exp.
Unless you are using sparc64 hardware.
flame:kargl[204] ./testl -V 2
ULP = 0.2670 for x = 2.000000000000000000000000000000000e+00
mpfr exp: 7.389056098930650227230427460575008e+00
libm exp: 7.389056098930650227230427460575008e+00
--
Steve
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