anchor.diff:  !###################################################################################
   !
   !*boundary_conditions:* Defines boundary conditions for prq problems
  - subroutine boundary_conditions(ADD,FIX,bc_type,grav_type,grav_vect,density,inletbc,outletbc,&
  + subroutine boundary_conditions(ADD,FIX,bc_type,grav_vect,density,inletbc,outletbc,&
          depvar_at_node,depvar_at_elem,prq_solution,mesh_dof)
    use arrays,only: dp,num_elems,num_nodes,elem_nodes,elem_cnct,node_xyz,units,&
           num_units
  
positive.code: vessel_type='elastic_g0_beta'
  mechanics_type='linear'
  bc_type='pressure'
  grav_type='on'
  
  if (vessel_type.eq.'rigid') then
      elasticity_parameters=0.0_dp
  
negative.code:     sub_name = 'calc_sparse_1dtree'
      call enter_exit(sub_name,1)
  !Initialise matrices and indices
  
      SparseCol=0
      SparseRow=1
      SparseVal=0.0_dp
  