anchor.diff:  ! ==============================================================================
   !  Variable friction module
   !
  -!    This module contains storage and routines for dealing with variable 
  +!    This module contains storage and routines for dealing with variable
   !    friction fields in GeoClaw.
   !
   !    If variable_friction > 0 then the data located here will override the basic
  
positive.code:             ! Assumes a uniform rectangular grid of data values.
              case(1)
                  stop "Unimplemented file type for friction files."
              
              ! ================================================================
              ! ASCII file with header followed by z data
              ! (progressing from upper left corner across rows, then down)
  
negative.code:         ! Locals
          integer :: m,i,j,k
          real(kind=8) :: x, y
          LOGICAL*1, INTENT(in) :: is_ghost
          INTEGER, INTENT(in) :: nghost, mint
  
  
          if (variable_friction) then
              ! Set region based coefficients
              do m=1, num_friction_regions
                  do i=1 - num_ghost, mx + num_ghost
                      do j=1 - num_ghost, my + num_ghost
                          if (is_ghost .and. ghost_invalid(i,j,mx,my,nghost,mint)) then
                              cycle
                          endif
                          x = xlower + (i-0.5d0) * dx
                          y = ylower + (j-0.5d0) * dy
                          if (friction_regions(m)%lower(1) < x .and.   &
  