Re: Use common_factor.hpp?

From: Moore, Paul (paul.moore_at_[hidden])
Date: 2001-12-13 09:23:12

>>> BTW[2], I see no performance or dependency notes for
>>> the new GCD library (such as the rational library has).
>>> I'm not sure what implication this has on the rational
>>> class documentation, as now I cannot be explicit about
>>> performance or dependencies whenever I use gcd()
>>> (basically, everywhere). Can performance and dependency
>>> notes be added to the gcd library? And can someone check
>>> that no new dependencies, or worse performance, is added
>>> by the new library. I can then just point the rational
>>> documentation at the gcd documentation.
>>
>> Daryle?
>
>The new GCD function basically uses the same algorithm
>currently in the rational header. There is about 5 inline
>function call indirections, which should be optimized
>out. For dependencies, the rational header #includes
>a lot more headers than the GCD/LCM header. The only
>potential problem is that the rational header doesn't
>use std::numeric_limits, and the GCD/LCM header does use
>std::numeric_limits and needs its constants at compile
>time.
>
>Another difference is that the rational version always
>includes sign compensation, but the stand-alone version
>only has sign compensation if the type signals sign-ness
>with std::numeric_limits. Unknown types get a sign-ignorant
>version, which may lead to sign errors if the unknown type
>is really a signed number type.

Will you put this in the GCD documentation? I don't want to chop that chunk
out of rational and replace it with "see the GCD documentation" if the user
will then find it's not there...

Thanks,
Paul.