Re: [boost] [metamath] Plans for compile time double

From: Chris Weed (chrisweed_at_[hidden])
Date: 2005-09-02 08:58:26

On 8/31/05, Peder Holt <peder.holt_at_[hidden]> wrote:
> On 8/30/05, Chris Weed <chrisweed_at_[hidden]> wrote:
> > On 8/27/05, Peder Holt <peder.holt_at_[hidden]> wrote:
> > > On 8/26/05, Chris Weed <chrisweed_at_[hidden]> wrote:
> > > > Hi,
> > > > I was wonder what the plans are for the compile time double library, metamath.
> > > > Is there a plan to develop compile time versions of the functions in
> > > > math.h, such as sin, cos, pow, abs, etc.?
> > > > Thanks,
> > > > Chris
> > > >
> > >
> > > That was the plan, yes. An implementation of some math functions
> > > already exists under
> > > http://boost-sandbox.sourceforge.net/vault/ <expaler/mpl_math.zip>
> > > I have modified the sine function to work with the compile time double
> > > library, but the main problem has been lack of time.
> > > I will try to find time to implement more math metafunctions, but help
> > > is welcome.
> > >
> > > Attached are implementations of sine and power (only integral
> > > exponents supported for now)
> > >
> > > Regards,
> > > Peder
> > >
> >
> > Hi,
> > I would like to help out with this. Was the plan to implement most of
> > the trigonometric functions with taylor expansions or some other
> > algorithm?
> 
> Great! Thanks.
> I'll upload the source to the sandbox cvs.
> 
> Cromwell has implemented cosine,sine and sqare root. I have rewritten
> his sine implementation to use the _double_double meta-operators.
> 
> The idea is to use taylor expansions, but wherever there is another
> series that converge faster, this should of course be used.
> E.g. The only expansion I have found of pow(x,y) where x and y are
> floating point numbers, requires one to calculate the series of ln(x)
> and then exp(ln(x)*y). This is very costly.
> 
> Regards,
> Peder
> 

The sandbox seems to be hosed.
Chris