Re: [boost] big_integer cln and gmp

From: Joel Young (jdy_at_[hidden])
Date: 2004-05-14 08:25:51

--------
From: "Richard Peters" <r.a.peters_at_[hidden]>
> From: "Joel Young" <jdy_at_[hidden]>
> >
> > Feature Request:
> >
> > Can support for alternate numerics packages be specified in
> > the type declaration for big_integer rather then with
> > a macro?  I'd like to be able to have multiple implementations
> > declared in the same program.
> >
> > Joel
> 
> This can be done, but what is the reason to do use different types (besides
> easier testing)? My idea was to make one portable integer type, which could
> make use of the fastest library installed. That's why it uses macros to
> select its implementation. If you create a program which explicitly uses gmp
> or cln, then it's a nonportable program.

Many numerics packages use build time parameters to specify the number
type.  For large systems I find this frustrating as sooner or later you
might want to do one part of the app using the float version and another
with the double version.

In particular tho, this time it is mostly for testing purposes.
Communication between types could be done explicitly with conversion
to string or BCD (binary coded decimal) or whatever.

This is low priority tho.  Speed and correctness are much much more
important.

Joel