Help with testing 4.1.3
linuxman at nmt.edu
Sun Apr 25 05:32:32 CEST 2004
This seems like the same problem I'm having. mpfr.org reports a
bug-fixed sqrt() function but that is for (I believe) the newest version
of MPFR (and not for the one distributed with GMP-4.1.2. Can we upgrade
all of MPFR to the latest version for 4.1.3 to elevate these problems?
On Sun, 25 Apr 2004, Kevin Ryde wrote:
> Laurent Fousse <laurent at fousse.info> writes:
> > | mpfr_sqrt_ui differs from sqrt for a=891885598, rnd_mode=GMP_RNDZ
> > | sqrt gives 0x1.d2a1d0a4c79b2p+14, mpfr_sqrt_ui gives
> > | 0x1.d2a1d0a4c79b1p+14 (-1 ulp)
> Looks like it's sqrt() which is wrong. By my reckoning the root is
> 1D2A1D0A4C79B1FFD1... which rounded to zero should be ...b1 as per
> mpf_sqrt_ui rather than ...b2 per sqrt().
> Assuming fesetround has done it's job then it looks like sqrt is
> either broken or not meant to obey the hardware rounding mode. Such
> is the folly of relying on exact answers from the math library :-(.
> I'll disable that test.
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