anchor.diff:      sub_name = 'calc_sparse_1dtree'
       call enter_exit(sub_name,1)
   !Initialise matrices and indices
  +
       SparseCol=0
       SparseRow=1
       SparseVal=0.0_dp
  
positive.code:             endif
            else!notfix depvar2
              grav=0.d0
              if(grav_type.eq.'on') then
                do nj=1,3                                  
                   grav=grav+density*grav_vect(nj)*9810.0_dp*(node_xyz(nj,elem_nodes(1,ne))-node_xyz(nj,elem_nodes(2,ne)))
                enddo
              endif
                   if(nhs.EQ.1) THEN
                      RHS(nzz_row)=-prq_solution(depvar2,1)+grav
                   elseif(nhs.EQ.2) THEN
  
negative.code: !
  !*calc_press_area:* Calculates new radii based on pressure area relnships
  
  subroutine calc_press_area(grav_vect,KOUNT,depvar_at_node,prq_solution,&
      mesh_dof,vessel_type,elasticity_parameters,mechanics_type,mechanics_parameters)
  
      use indices
      use arrays,only: dp,num_nodes,num_elems,elem_field,elem_nodes,node_xyz
      use diagnostics, only: enter_exit
      character(len=60), intent(in) :: vessel_type
      character(len=60), intent(in) :: mechanics_type
      real(dp), intent(in) :: grav_vect(3)
  