PROGRAM MAIN
!
!     Example of reading cell corner locations from individual face files.
!     A single cell is a quadrilateral with corner points A,B,C,D.
!
!      D ( xg(i,j+1), yg(i,j+1) )           C ( xg(i+1,j+1), yg(i+1,j+1) )
!
!
!      A ( xg(i,j), yg(i,j) )               B ( xg(i+1,j), yg(i+1,j) )
!
!      For spherical polar coordinate system xg is longitude (with -179.99999,180.0 range) and 
!      yg is latitude (-90,90).
!

   
      IMPLICIT NONE

      INTEGER IUNIT
      REAL*8, ALLOCATABLE  :: XG(:,:), YG(:,:)
      INTEGER NX, NY
      INTEGER WORDLEN

!     gfortran needs wordlen = 8 for real*8
!     to compile: gfortran -fconvert=big-endian read_face_corner_coords.F90
      WORDLEN = 8
!     ifort 9 needs wordlen = 8 for real*8
!     to compile: ifort -convert big_endian read_face_corner_coords.F90
!     WORDLEN = 8

      IUNIT = 11
      NX = 511
      NY = 511
      ALLOCATE(XG(NX,NY))
      ALLOCATE(YG(NX,NY))

      OPEN(UNIT=IUNIT, FILE='tile001.mitgrid',  &
           ACCESS='DIRECT', RECL=NX*NY*WORDLEN,STATUS='OLD')
      READ(IUNIT,REC=6) XG
      READ(IUNIT,REC=7) YG
      PRINT *, 'MAXVAL(XG), MINVAL(XG) = ', MAXVAL(XG), MINVAL(XG)
      PRINT *, 'MAXVAL(YG), MINVAL(YG) = ', MAXVAL(YG), MINVAL(YG)
      CLOSE(IUNIT)

      OPEN(UNIT=IUNIT, FILE='tile002.mitgrid',  &
           ACCESS='DIRECT', RECL=NX*NY*WORDLEN,STATUS='OLD')
      READ(IUNIT,REC=6) XG
      READ(IUNIT,REC=7) YG
      PRINT *, 'MAXVAL(XG), MINVAL(XG) = ', MAXVAL(XG), MINVAL(XG)
      PRINT *, 'MAXVAL(YG), MINVAL(YG) = ', MAXVAL(YG), MINVAL(YG)
      CLOSE(IUNIT)

      OPEN(UNIT=IUNIT, FILE='tile003.mitgrid',  &
           ACCESS='DIRECT', RECL=NX*NY*WORDLEN,STATUS='OLD')
      READ(IUNIT,REC=6) XG
      READ(IUNIT,REC=7) YG
      PRINT *, 'MAXVAL(XG), MINVAL(XG) = ', MAXVAL(XG), MINVAL(XG)
      PRINT *, 'MAXVAL(YG), MINVAL(YG) = ', MAXVAL(YG), MINVAL(YG)
      CLOSE(IUNIT)

      OPEN(UNIT=IUNIT, FILE='tile004.mitgrid',  &
           ACCESS='DIRECT', RECL=NX*NY*WORDLEN,STATUS='OLD')
      READ(IUNIT,REC=6) XG
      READ(IUNIT,REC=7) YG
      PRINT *, 'MAXVAL(XG), MINVAL(XG) = ', MAXVAL(XG), MINVAL(XG)
      PRINT *, 'MAXVAL(YG), MINVAL(YG) = ', MAXVAL(YG), MINVAL(YG)
      CLOSE(IUNIT)

      OPEN(UNIT=IUNIT, FILE='tile005.mitgrid',  &
           ACCESS='DIRECT', RECL=NX*NY*WORDLEN,STATUS='OLD')
      READ(IUNIT,REC=6) XG
      READ(IUNIT,REC=7) YG
      PRINT *, 'MAXVAL(XG), MINVAL(XG) = ', MAXVAL(XG), MINVAL(XG)
      PRINT *, 'MAXVAL(YG), MINVAL(YG) = ', MAXVAL(YG), MINVAL(YG)
      CLOSE(IUNIT)

      OPEN(UNIT=IUNIT, FILE='tile006.mitgrid',  &
           ACCESS='DIRECT', RECL=NX*NY*WORDLEN,STATUS='OLD')
      READ(IUNIT,REC=6) XG
      READ(IUNIT,REC=7) YG
      PRINT *, 'MAXVAL(XG), MINVAL(XG) = ', MAXVAL(XG), MINVAL(XG)
      PRINT *, 'MAXVAL(YG), MINVAL(YG) = ', MAXVAL(YG), MINVAL(YG)
      CLOSE(IUNIT)

      END