static char help[] = "Tests the DMShellCreate() and PetscSectionCreate() for fieldsplit initialization.";

#include "petscdmshell.h" 
#include "petscvec.h" 

int main(int argc, char **argv)
{
  int              i;
  PetscInt         numeq = 10, start = 1, NF, NE, numFields = 2, numDof, numComp;
  PetscErrorCode   ierr;
  DM               FSDM;
  PetscScalar      value;
  PetscSection     FSSection;
  int              field1inds[6], field2inds[4];
  
  // We have a problem with 10 equations, i.e. 10dofs.
  // These dofs belong to two fields (field1 has 6dofs and field2 has 4dofs).
  // Here is a mapping from field dofs to global dofs
  field1inds[0] = 1;
  field1inds[1] = 2;
  field1inds[2] = 4;
  field1inds[3] = 6;
  field1inds[4] = 7;
  field1inds[5] = 9;
  
  field2inds[0] = 3;
  field2inds[1] = 5;
  field2inds[2] = 8;
  field2inds[3] = 10;
  
  // We would like to use a DMShell to represent this data structure.
  // To do so we start by creating a section with 10points having one dof each.
  PetscInitialize(&argc,&argv,(char*)0,help);
  
  ierr = PetscSectionCreate(PETSC_COMM_WORLD, &FSSection);
  ierr = PetscSectionSetChart(FSSection, start, numeq+1);
  ierr = PetscSectionGetChart(FSSection, &NF, &NE);
  printf("start=%i, End=%i.\n",NF,NE);
  
  for(i=0; i<numeq; i++)
    {
      ierr = PetscSectionSetDof(FSSection, i+1, 1); // <---- here we think we assign a dof per point?
    }
  PetscSectionView(FSSection, PETSC_VIEWER_STDOUT_WORLD);
  
  
  ierr = PetscSectionSetNumFields(FSSection, numFields);  // <---- We create the two fields
  /* ierr = PetscSectionSetFieldDof(FSSection, 1, 1, 1);   <--- We would like to associate dof 1 of point 1 to field 1, but we get an error? */
  /* PetscSectionView(FSSection, PETSC_VIEWER_STDOUT_WORLD); */
  
  /* ierr = PetscSectionSetUp(FSSection); */
  /* ierr = DMShellCreate(PETSC_COMM_WORLD,FSDM); */
  /* ierr = DMSetDefaultSection(FSDM,FSSection); */
  /* ierr = DMView(FSDM,PETSC_VIEWER_STDOUT_SELF); */
  
  /* ierr = DMDestroy(&FSDM); */
  ierr = PetscSectionDestroy(&FSSection);
  return 0;
}