Supersample

supersample.f90

program supersample_fac

    implicit none

    integer :: i, j, ii, jj
    integer :: supersample
    integer :: tile_nx, tile_ny
    integer :: tile_bdr
    real :: lat, lon, latp, lonp
    real :: known_lat
    real :: dx

    tile_nx = 1200
    tile_ny = 1200
    supersample = 3
    tile_bdr = 3

    do j = supersample * tile_bdr + 1, supersample * (tile_ny + tile_bdr), 1
        do i = supersample * tile_bdr + 1, supersample * (tile_nx + tile_bdr), 1
            ii = (i - 1) / supersample + 1
            jj = (j - 1) / supersample + 1

            call tile_to_latlon(j, i, lat, lon, 3)
            call tile_to_latlon(jj, ii, latp, lonp, 1)

            if (lat /= latp .or. lon /= lonp) then
                write(0,*) 'Not equal!'
                write(0,*) 'First: ', i, j, lat, lon
                write(0,*) 'Second: ', ii, jj, latp, lonp
                stop
            endif
        enddo
    enddo

    contains


    subroutine tile_to_latlon(j, i, lat, lon, supersample)
        
        implicit none

        integer, intent(in) :: j, i
        real, intent(out) :: lat, lon
        integer, intent(in) :: supersample

        integer :: tile_x, tile_y ! Start of tile
        real :: known_lat, known_lon
        real :: dx, dy

        tile_x = 1
        tile_y = 1201
        known_lat = 89.975
        known_lon = -179.975
        dx = 0.05
        dy = 0.05

        lon = known_lon + real(i - (supersample * tile_bdr + 1) + (supersample * (tile_x - 1))) * dx / supersample
        lat = known_lat + real(j - (supersample * tile_bdr + 1) + (supersample * (tile_y - 1))) * dy / supersample


    end subroutine tile_to_latlon

end program supersample_fac