On 6/10/05, David Abrahams <dave@boost-consulting.com> wrote:
Peder Holt <peder.holt@gmail.com> writes:
c.f. http://gcc.gnu.org/ml/gcc/2005-01/msg01744.html and the last two items here: http://gcc.gnu.org/onlinedocs/gcc-4.0.0/gcc/Deprecated-Features.html#Depreca...
Oh, well. Anyway, I have now uploaded a version of this to the vault: metamath.zip that is mpl-compliant and supports comparison and arithmetics with the same accuracy as normal double arithmetics. Does not support NaN.
Does it get around the comparison problem somehow?
I think the results when a floating point value is converted to an integral that can't represent it are undefined (or something similar) but at least most compilers won't stop you. You might try to do some awful thing like transforming
a < b
into
long(b - a) > 0
I am not quite sure I understand the problem correctly. What I do is the following: BOOST_STATIC_CONSTANT(bool,value=(BOOST_DOUBLE_EVAL(N1)<BOOST_DOUBLE_EVAL(N2))); So the comparison is not a very big problem. If you absolutely don't want to evaluate the double expression, you would have to do something like: if N1::exp < N2::exp then true if N1::exp > N2::exp then false if N1::decimals1 < N2::decimals then true if N1::decimals1 > N2::decimals then false if N1::decimals2 < N2::decimals then true if N1::decimals2 > N2::decimals then false false Same goes for addition and subtraction, and arguably also multiplication. I am not sure how to avoid double-evaluation in division, but it is probably possible. But, on the other hand, if you are talking about tolerances, I have not implemented any support for a rounding-error tolerant version of compare, I just mimic the behaviour of double. Regards, Peder.
-- Dave Abrahams Boost Consulting www.boost-consulting.com
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