On 10/25/06, Bill Hart <[EMAIL PROTECTED]> wrote:
>
> When asked 61/3.0, SAGE returns:
>
> 20.333333333333332
>
> Now I understand that floating point numbers are often rounded down to
> prevent floating point drift. But I was wondering if rounding it down
> in the manner above is quite necessary. Perhaps that last 2 should be a
> 3.
This is how mpfr behaves. What you want to do is
sage: RR = RealField(rnd='RNDU') ; RR(61/3.0)
20.333333333333333
When you execute '61/3.0', it's executed as
sage: preparse('61/3.0')
"Integer(61)/RealNumber('3.0')"
which is slightly wrong. Hope that helps.
BTW, there is a tiny bug in rings/real_mpfr.pyx. In the documentation,
it says that the default precision is RNDU (round to + \inf), but it's
actually set to RNDN...
didier
>
> Bill.
>
>
> >
>
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