Boost C++ Libraries: Ticket #7879: Optimize equality comparison

type changed

Thu, 10 Jan 2013 23:23:41 GMT

type Bugs → Feature Requests

Fri, 11 Jan 2013 15:44:23 GMT

Also, as I see, rational<IntType>::operator< is overcomplicated. It uses some complex algorithm, I think it is to prevent overflow. But with arbitrary-sized integers it can be as simple as a.num*b.den < b.num*a.den (and also we need to take care about signs). It should be faster than current algorithm that uses divisions.

John Maddock — Sat, 12 Jan 2013 11:08:58 GMT

You're correct of course, in fact rational_adapter is needlessly slow because of it's dependence on Boost.Rational which often performs a lot of unnecessary copying.

I really need to rewrite rational_adapter not to use Boost.Rational at all.

BTW the front end does have the ability to optimize comparisons when a full compare is expensive, but since we can't access the numerator and denominator of Boost.Rational without copying, it's unlikely to help so much as it should.

Domagoj Šarić — Fri, 11 Oct 2013 13:07:14 GMT

Wouldn't it be more worth while to merge this effort with improving Boost.Rational ('to kill more flies with a similar amount of effort)?