anchor.diff:    real(WP), parameter :: ARTIFICIAL_PRESSURE_STRENGTH = 1.0e-5_WP
     real(WP)  :: ARTIFICIAL_PRESSURE_RADIUS, PRESSURE_RADIUS_FACTOR
     logical, parameter :: USE_SURFACE_TENSION = .false.
  +  real(WP), parameter :: STC = 0.0078
   
   
   end module constants
  
positive.code: 
  
    c = 45.0_WP*mass/PI/h5*BULK_MODULUS*0.5_WP
    Csurf = 315.0_WP/64.0_WP/PI/h9
  
    do i = 1, n
      sx = 0.0_WP
      sy = 0.0_WP
      sz = 0.0_WP
      scorr = 0.0_WP
  
  
      ! Compute pressure
      l = nc(i)
  
negative.code:           * (rho(i)+rho(nb)-2.0_WP*PARTICLE_DENSITY) &
            * q / m
  
        sx = sx + k*dx
        sy = sy + k*dy
        sz = sz + k*dz
  
      end do
  
  