CHARACTER(LEN=4) FUNCTION label4(indx)
Implicit None

!=================================================================
! Function to obtain a character string used to label files from an
!    integer iterator.

!CHARACTER(LEN=4) :: label4
INTEGER :: indx

   IF (indx.lt.10)                    WRITE(label4,'("000",I1)') indx
   IF (indx.ge.10.and.indx.lt.100)   WRITE(label4,'("00",I2)') indx
   IF (indx.ge.100.and.indx.lt.1000) WRITE(label4,'("0",I3)') indx
   IF (indx.ge.1000)                  WRITE(label4,'(I4)') indx

End Function label4