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Thu, 29 Mar 2001 08:00:51 +0200
Kevin Ryde <address@hidden> writes:
> Well, there should be 53 bits of precision on that log, which should
> be enough.
> I'm unable to reproduce that on a ppc604e (or an i386), I get ...78 as
> expected. Is the compiler giving the right value for chars_per_bit?
> printf ("%A\n", __mp_bases.chars_per_bit_exactly);
> should print 0X1.34413509F79FFP-2 by my reckoning.
I get 0X1.34413509F79FDP-2 on my machine which I think explains the
issue. For some reason 2 of those 53 bits get lost. But even with 53
bits of precision I see no proof that the original problem cannot occur.
> But your point is taken though, it'd be better not to depend on
> floating point for this. A fixed point integer approximation would
> make it easier to guarantee the results, and would also hopefully make
> it possible to address the problem with 64-bit mpf exponents noted in
The problem is that I want to use the function for a math library. So I
want it to be correct or, at least, know the range in which it is
Perhaps the following is helpful:
bash-2.03$ gcc -v
Reading specs from /usr/lib/gcc-lib/powerpc-suse-linux/2.95.2/specs
gcc version 2.95.2 19991024 (release)
bash-2.03$ uname -a
Linux tohu 2.2.14 #1 Tue May 30 01:15:50 GMT 2000 ppc unknown
machine Power Macintosh
- mpz_sizeinbase, Winfried Dreckmann, 2001/03/27
- Re: mpz_sizeinbase,
Winfried Dreckmann <=