________________________________
> From: jwpeter...@gmail.com
> Date: Mon, 22 Aug 2016 08:28:18 -0600
> Subject: Re: [Libmesh-users] DenseSubMatrix and DenseSubVector lack of
> ctor and operators
> To: marchy...@hotmail.com
> CC: libmesh-users@lists.sourceforge.net
>
>
>
> On Mon, Aug 22, 2016 at 7:53 AM, Mike Marchywka
> <marchy...@hotmail.com<mailto:marchy...@hotmail.com>> wrote:
> I was trying to move some code around related to the vars typically
> called Ke and Fe
> but encountered several errors due to missing ctor or operators such as
> assignment.
> Can someone comment on the benefit of or need for these restrictions?
>
> I think you are probably referring to a default constructor for
> DenseSubMatrix, i.e. one that does not need a reference to a parent
> matrix in order to be created? I don't think this is a good
> idea/necessary, as it would introduce extra bookkeeping and potentially
> make DenseSubMatrix too easy to use incorrectly...
>
>
> I was trying to clean up
> my own code a bit and debating about how to handle things which seem to often
> be compile time constants. One possibility is to create a code generator that
> creates specific c++ code for a given set of conditions. This is ok if
> there are some
> compiler optimizations that just not easy with other approaches. Thanks.
>
>
>
> DMN Ke; DVN Fe;
> //DSM Ke_var; DSV Fe_var;
> DSM Ke_var; // [mla.nvar][mla.nvar];
> DSV Fe_var; // [mla.nvar] ;
> // InitMats(Ke,Fe,Ke_var,Fe_var,mla.nvar);
>
> What specifically is a compile-time constant limitation here from libmesh?
>
>
>
> //const IdxTy dofsz=dof_indices.size();
> //const IdxTy dofsz=mla.di.dof_indices_var[0].size();
> //Ke.resize (dofsz,dofsz); Fe.resize (dofsz);
> /*
> DSM Ke_var[mla.nvar][mla.nvar] =
> {
> { DSM(Ke), DSM(Ke), DSM(Ke), DSM(Ke)},
> { DSM(Ke), DSM(Ke), DSM(Ke), DSM(Ke)},
> { DSM(Ke), DSM(Ke), DSM(Ke), DSM(Ke)},
> { DSM(Ke), DSM(Ke), DSM(Ke), DSM(Ke)}
> };
>
> DSV Fe_var[mla.nvar] = {DSV(Fe), DSV(Fe), DSV(Fe), DSV(Fe) };
>
> Are you just wanting to know how to create dynamically-size 2D arrays
> at runtime?
Yes, I guess that would do it but then the question is why
the examples differ from that method. Certainly compile time
does give the compiler more opportunities to optimize.
There is any object that can do this internally,
Ty * Ke_var_data = new Ty[n*m] ?
and I would have guessed that for best performance you have some way of
organizing memory.
>From what I have now, I only need to be able to interface to these things from
>the
function that assembles the FEM RHS and LHS,
dof_map.constrain_element_matrix_and_vector (Ke, Fe, dof_indices);
system.matrix->add_matrix (Ke, dof_indices);
system.rhs->add_vector (Fe, dof_indices);
I could probably check the documentation but are any of there templated or
accept iterators
or do they require these libmesh DenseSub types?
Thanks.
>
> --
> John
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