convert_sizes_to_offsets Subroutine

   PURE SUBROUTINE convert_sizes_to_offsets(sizes, &
                                            offsets_start, offsets_stop)
      !! Converts sizes to offsets

      INTEGER, DIMENSION(:), INTENT(IN)                  :: sizes
         !! array with sizes
      INTEGER, DIMENSION(:), INTENT(OUT)                 :: offsets_start
         !! offsets of starts
      INTEGER, DIMENSION(:), INTENT(OUT), OPTIONAL       :: offsets_stop
         !! offsets of ends

      INTEGER                                            :: i, n

!   ---------------------------------------------------------------------------

      n = SIZE(sizes)
      IF (n .GT. 0) THEN
         offsets_start(1) = 1
         IF (PRESENT(offsets_stop)) offsets_stop(1) = sizes(1)
         IF (.NOT. PRESENT(offsets_stop)) THEN
            DO i = 2, n
               offsets_start(i) = offsets_start(i - 1) + sizes(i - 1)
            END DO
            IF (SIZE(offsets_start) .GT. n) &
               offsets_start(n + 1) = offsets_start(n) + sizes(n)
         ELSE
            DO i = 2, n
               offsets_start(i) = offsets_start(i - 1) + sizes(i - 1)
               offsets_stop(i) = offsets_stop(i - 1) + sizes(i)
            END DO
            IF (SIZE(offsets_start) .GT. n) &
               offsets_start(n + 1) = offsets_start(n) + sizes(n)
         END IF
      ELSE
         IF (.NOT. PRESENT(offsets_stop)) THEN
            offsets_start(1) = 0
         END IF
      END IF
   END SUBROUTINE convert_sizes_to_offsets