---------- Forwarded message ----------
From: John Peterson <[EMAIL PROTECTED]>
Date: Sat, Oct 18, 2008 at 3:54 PM
Subject: Re: [Libmesh-users] fe reinit
To: Manav Bhatia <[EMAIL PROTECTED]>


On Sat, Oct 18, 2008 at 3:13 PM, Manav Bhatia <[EMAIL PROTECTED]> wrote:
>
> Why would non-affine maps affect the memory footprint regarding caching of
> information?

It doesn't affect the memory, it effects the amount of computation
which needs to be done during reinit.  (When the map is affine, the
Jacobian need only be computed at one quadrature point, and re-used
everywhere. Roy has implemented this "has_affine_map" optimization.)
I brought this up in regard to your original question about time
performance, in trying to figure out what reinit is spending the most
time doing.


> Since my mesh geometry does not change during the course of the computation,
> I think storing the N, dN/dx, dN/dy and dN/dz for the different quadrature
> points should work. (I do not need second order derivatives). I can either

This only works if all your elements have exactly the same shape.  If
that's the case, Roy has also implemented a "cached_nodes_still_fit"
optimization that should already be doing what you suggest.  If reinit
is taking a long time, we need to see which of these optimizations is
not in effect, and why.

--
John



-- 
John

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