Re: [boost] [metamath] Using mpl::numeric_cast

From: Peder Holt (peder.holt_at_[hidden])
Date: 2005-09-21 12:20:54

On 9/21/05, Cromwell Enage <sponage_at_[hidden]> wrote:
> --- Peder Holt wrote:
> > Definitely an improvement.
> >
> > Perhaps it would be a good idea to move the entire
> > metamath/double implementation to the mpl/math
> > directory?
>
> Agreed.  The question now is where main development
> should continue: the Sandbox CVS or the Boost Vault
> <http://boost-consulting.com/vault/>.
>

Btw.

My initial motivation for developing the compile time double, was to
be able to implement an expression library on top of it, supporting
differentiation and simple equation solving.

typedef times<sine<_1>,_1> fn;
typedef differentiate<fn,_1> dfn;
typedef apply<dfn,pi> number;

I haven't been able to implement this without adding a function_tag
typedef to all metafunctions.
plus -> plus_tag
sine -> sine_tag

In addition, it would be great to have fusion-support inplace, allowing:
BOOST_AUTO(fn,sin(_1)*_1);
BOOST_AUTO(dfn,diff(fn,_1));
and in turn:
double result=dfn(pi());
or
typedef BOOST_TYPEOF(dfn) tdfn;
typedef apply<tdfn,pi> number;

The fundamental fusion support is something that could be part of the
mpl_math library.

Regards,
Peder

>                               Cromwell D. Enage
>
>
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