anchor.diff:        np=elem_nodes(1,ne)
         ny=depvar_at_node(np,0,1)
         G_PLEURAL=0.0_dp    !gravitational force
  -      if(grav_type.eq.'on')then
  -        do nj=1,3
  -          HEIGHT(nj)=node_xyz(nj,np)-node_xyz(nj,1) !ARC - where to put grav reference height?
  -          G_PLEURAL=G_PLEURAL+mechanics_parameters(2)*grav_vect(nj)*9810.d0*HEIGHT(nj) !kg
  -       enddo
  -      endif
  +      do nj=1,3
  +        HEIGHT(nj)=node_xyz(nj,np)-node_xyz(nj,1) !ARC - where to put grav reference height?
  +        G_PLEURAL=G_PLEURAL+mechanics_parameters(2)*grav_vect(nj)*9810.d0*HEIGHT(nj) !kg
  +      enddo
         Ppl=mechanics_parameters(1)-G_PLEURAL !Pa
         Pblood=prq_solution(ny,1)! Pa
         Ptm=Pblood+Ppl     ! Pa
  
positive.code: !
  !*calc_press_area:* Calculates new radii based on pressure area relnships
  
  subroutine calc_press_area(grav_type,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) :: grav_type
      character(len=60), intent(in) :: vessel_type
      character(len=60), intent(in) :: mechanics_type
      real(dp), intent(in) :: grav_vect(3)
  
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
  