anchor.diff:  
               do i=1, nx
                   curpos = find_location(lo, hi%lat(i,j), hi%lon(i,j), lastpos)
  +
                   if (curpos%x<1) then
                       ! something broke, try assuming that the grids are the same possibly wrapping (for ideal)
                       write(*,*) "Error in Geographic interpolation, check input lat / lon grids", i,j
  
positive.code:         ! note that the final weights are a mixture of the x and y weights
          bilin_weights=(/x1*f2,x0*f2,x3*f1,x2*f1/)
      end function bilin_weights
  
      !>------------------------------------------------------------
      !! Find the minimum x
  
negative.code: !!------------------------------------------------------------
  module geo
      use data_structures
      use io_routines, only:io_write
      implicit none
  
      private
  