On Thu, 26 Oct 2006 14:39:13 -0500, Bill Hart <[EMAIL PROTECTED]> wrote:
>
> I would say that computing more bits would be less confusing. I use the
> general rule of thumb that 10 bits equals 3 decimal digits. At present,
> SAGE seems to be out on the last digits, I think the answer is R(10/3)
> = 3.33333333333335 bits. :-)
>
> On a more serious note, sage currently claims to be working to 53 bits
> accuracy which is 16 decimal digits, but it actually supplies 17
> significant digits. It is possible that were this fixed, the problem
> would vanish.
>
> Incidentally, is there a way of changing the *default* precision in
> SAGE (at runtime) from 53 bits? I couldn't find this in the manual
> after an extensive search.
The default RR is 53 bits. If you type RealField() you get that because
of this line in <SAGE_DEVEL>/sage/sage/rings/real_mpfr.pyx:
def __init__(self, int prec=53, int sci_not=0, rnd="RNDN"):
This default does *not* even affect numerical literals, which depend on the
precision to which they are input:
sage: parent(13.0302000000000000000000000000000000000000000000000)
Real Field with 172 bits of precision
Literals are parsed by the RealNumber command, which you can set to
whatever
you want (as I explained a day or two ago on sage-devel).
William
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