Mike: you seem overly concerned with optimization even though you are just getting started. Optimization is something better handled after you have your application working. Try to write good solid code that makes sense first.
Right now you are just guessing at what's going to be slow... the only way to know is to build your application and then use a profiler to see where the time is going and try to target those areas with optimization. For instance: if you are doing an implicit calculation then your linear solver and preconditioner are likely going to take up 80% (or more) of your solve time... so optimizing your FE assembly won't matter much. Now: that's not a reason to be sloppy... But libMesh has endured for ~15 years at this point and it's anything but sloppy. Just some advice... Derek On Mon, Aug 22, 2016 at 10:51 AM Mike Marchywka <marchy...@hotmail.com> wrote: > > > > > > ________________________________ > > 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 > > > ------------------------------------------------------------------------------ > _______________________________________________ > Libmesh-users mailing list > Libmesh-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/libmesh-users > ------------------------------------------------------------------------------ _______________________________________________ Libmesh-users mailing list Libmesh-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/libmesh-users
