[petsc-users] dmda and structures

[Barry Smith]

  DMDAVecGetArrayDOF() might serve your needs. You would access with realization_array[i][j]  for the ith grid point and j th realization

   Barry



On Dec 28, 2013, at 7:44 PM, Gideon Simpson <gideon.simpson at icloud.com> wrote:

> I'm trying to use 1D DMDA's to manage distributed monte carlo computations, and I've got the following problem.  If I know, in advance, how many floating points are needed for each realization, everything is fine.  But, if I want to be able to set this at run time, I can't get it to work.  What I have is:
> 
> typedef struct {
>  PetscScalar id;
>  PetscScalar *x;
> } Realization;
> 
> then, in the main part of the code:
> 
>  Realization *realization_array;
>  DM sim_data_da;
>  Vec sim_data_vec;
> 
>  PetscInt xsize=10, realization_dof, i;
>  PetscOptionsGetInt(NULL, "-xsize", &xsize, NULL);
> 
> realization_dof	  = xsize + 1;
> 
> 
>  DMDACreate1d(PETSC_COMM_WORLD,DMDA_BOUNDARY_NONE, batch_size, realization_dof, 0, NULL, &sim_data_da);
>  DMCreateGlobalVector(sim_data_da,&sim_data_vec);
> 
>  DMDAVecGetArray(sim_data_da, sim_data_vec, & realization_array);
> 
>  Up to this point, I have no problem, but, when I try to access realization_array[i].x[j], I get memory errors.  Is this fundamentally unworkable, or  is there a fix?
> 
> -gideon
>