dolfin team mailing list archive

[Matthew Knepley <knepley@xxxxxxxxx>]

On Mon, Mar 23, 2009 at 9:47 AM, A Navaei <axnavaei@xxxxxxxxxxxxxx> wrote:

> 2009/3/23 Matthew Knepley <knepley@xxxxxxxxx>:
> > I am going to agree with Garth here. There is no real difference. MTL4
> > uses the template engine to generate code. FFC uses Python. However,
> > both approaches only generate C++ code. They can be made equivalent
> > for any given problem. I am fairly sure the MTL guys would agree. I know
> > them very well.
>
> If you want to have a runtime code-generator which implements the
> features of compile-time template meta-programming one by one, such as
> loop unrolling, and in this way effectively end up with an equivalent;
> then the question is why re-inventing the wheel?


Template programming is awful. I have done a lot of it. The programming
constructs that generate efficient code are non-intuitive and just about
undebuggable. This is the whole point behind conceptGCC (also by the MTL
guys). Templates are good at some jobs, but very very bad at others.

  Matt


>
> The compile-time has the benefit of avoiding double-compilation (lib +
> jit) and implementing a code generator. Whether the above concepts are
> the same or not, my original question is still unanswered: what's the
> benefit of FFC runtime code-generation over compile-time template
> meta-programming? Note that the form DSL can be still used with the
> latter approach and it's not specific to FFC.
>
>
> -Ali
>
> >
> >    Matt
> >
> >>
> >> -Ali
> >>
> >> >
> >> > Garth
> >> >
> >> >> Without having a concrete meta-programming implementation, it may be
> >> >> impossible to predict how much performance one would gain compared to
> >> >> FFC. However, MTL4 has been reported to be many times faster than
> >> >> code-generation means such as ATLAS.
> >> >>
> >> >> Based on this, are there any specific benefits in FFC code-generation
> >> >> which may not be covered by meta-programming?
> >> >>
> >> >>
> >> >> -Ali
> >> >> _______________________________________________
> >> >> DOLFIN-dev mailing list
> >> >> DOLFIN-dev@xxxxxxxxxx
> >> >> http://www.fenics.org/mailman/listinfo/dolfin-dev
> >> >
> >> >
> >> >
> >> _______________________________________________
> >> DOLFIN-dev mailing list
> >> DOLFIN-dev@xxxxxxxxxx
> >> http://www.fenics.org/mailman/listinfo/dolfin-dev
> >
> >
> >
> > --
> > What most experimenters take for granted before they begin their
> experiments
> > is infinitely more interesting than any results to which their
> experiments
> > lead.
> > -- Norbert Wiener
> >
>



-- 
What most experimenters take for granted before they begin their experiments
is infinitely more interesting than any results to which their experiments
lead.
-- Norbert Wiener