On 08/30/2011 03:00 PM, John Peterson wrote:
> On Tue, Aug 30, 2011 at 1:57 PM, Truman Ellis <[email protected]> wrote:
>> I have a question about FEMSystem::init_context and inherited instances like
>> NavierSystem::init_context from example 18. Why is it necessary to call
>> get_JxW(), get_phi(), etc? In FEMSystem::assembly() this is only called once
>> before we have actually started looping over any elements. Furthermore, all
>> of the get_* functions are actually called again in the appropriate
>> *_time_derivative, and *_constraint functions. I believe they are
>> appropriate in this latter case because a specific element has been
>> specified at this point. I tried commenting out this block of code in ex18,
>> and it doesn't appear to break anything. Can anyone explain if and what the
>> purpose of this code is?
> This tells the FE object that we will need the JxW, phi, etc values
> eventually, and that it should compute them.
>
> Here's the get_phi() implementation. Note that it sets the calculate_phi
> flag.
>
> const std::vector<std::vector<Real> >& get_phi() const
> { libmesh_assert(!calculations_started || calculate_phi);
> calculate_phi = true; return phi; }
>
So it is a performance issue? How does this handle p-adaptivity?
--
Truman Ellis
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