c-------------- Converting direct access files to .txt files ----------------

      SUBROUTINE dat_to_txt
      COMMON /size/ N1, ial
      PARAMETER(Nmax=999)
      DIMENSION ia(Nmax+1), di(Nmax), al(Nmax*Nmax), vec(Nmax)

      OPEN (1, FILE='ia.txt',  ERR=1)
      OPEN (2, FILE='di.txt',  ERR=1)
      OPEN (3, FILE='al.txt',  ERR=1)
      OPEN (4, FILE='vec.txt', ERR=1)

      OPEN (5, FILE='ia.dat',  ACCESS='DIRECT', RECL=4, ERR=2)
      OPEN (6, FILE='di.dat',  ACCESS='DIRECT', RECL=4, ERR=2)
      OPEN (7, FILE='al.dat',  ACCESS='DIRECT', RECL=4, ERR=2)
      OPEN (8, FILE='vec.dat', ACCESS='DIRECT', RECL=4, ERR=2)

      DO i=1, N1+1
         READ (5, REC = i) ia(i)
         WRITE (1, *) ia(i)
      ENDDO
      ial = ia(N1+1)-1

      DO i=1, N1
         READ  (6, REC = i) di(i)
         WRITE (2, *) di(i)
      ENDDO

      DO i=1, ial
         READ  (7, REC = i) al(i)
         WRITE (3, *) al(i)
      ENDDO

      DO i=1, N1
         READ  (8, REC = i) vec(i)
         WRITE (4, *) vec(i)
      ENDDO

      CLOSE(1)
      CLOSE(2)
      CLOSE(3)
      CLOSE(4)
      CLOSE(5)
      CLOSE(6)
      CLOSE(7)
      CLOSE(8)
      GOTO 3
    1 STOP 'Input error: check the input files.'
    2 STOP 'Output error: failed to create direct access file.'
    3 END