Re: [boost] [MPL.Math] updates for double

From: Cromwell Enage (sponage_at_[hidden])
Date: 2005-11-09 12:10:44

--- Peder Holt wrote:
> --- Cromwell Enage wrote:
> > There's an existing implementation of arctangent
> > that should work for all real numbers.

Correction: it also only converges for |x| <= 1.

> I didn't notice. I'll check it out an look at its
> convergence rate.

It's the Maclaurin series, and it's rather slow.

> > If all interested parties agree with this plan,
> > the next question is, where should we put pi<>? 
So
> > far, I have two candidates:
> >
> > * boost::mpl::math, since zero<> also resides
> >   there
> > * boost::mpl::math::constants
> 
> boost::mpl::math, then probably.

I'll take a shot at it for the next update.

> > Only backward-compatibility concerns have held me
> > back from employing this technique elsewhere.  (I
> > don't have a Class B compiler on-hand though, so I
> > don't know if my fears are unjustified.)
> 
> Don't think this is an issue.
> MSVC6.5 at least prefers BOOST_STATIC_CONSTANT, as
> they are much easier to handle than excessive
> template instantiations.

Noted.

> > I'll #ifdef 0 out the code to be replaced.
> 
> Ok.

And what did I do instead?  I reimplemeted a majority
of the advanced metafunctions by using
Boost.Preprocessor to unroll the recursion.  (You must
now #define the corresponding limit macro for each
metafunction, and you have a hard limit of 255
depending on the metafunction, but it beats exceeding
the template instantiation depth.)  Best of all,
euler.cpp compiles and works just fine.

                              Cromwell D. Enage

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