On 10/25/05, Cromwell Enage <sponage@yahoo.com> wrote:
--- Peder Holt wrote:
I think the results are to be expected, if I understand them correctly.
Okay.
1. BOOST_MPL_MATH_DOUBLE uses built-in double arithmetics to extract the mantissa and the exponent at compile time. Since the mantissa of double is limited to 52 bits, it uses rounding to get a best match.
2. string_c_to_double on the other hand has ~60 bits available.
Should I then change big_integral_mantissa, whole_part, and rational_part to account for the extra bits?
It wouldn't hurt, I guess. More accurate results should make more people happy. Peder.
The only way to get these results to match, is to reintroduce the strict rounding to 52 bits on all double_'s but this would lead to a less-than-52-bit precision on mathematical functions such as sine.
We could of course also limit string_c_to_double's built in precision to 52 bits, but it seems such a waste to throw away the extra information :)
Indeed!
Cromwell D. Enage
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