      SUBROUTINE FFT1(A,B,N,ISN,IERR)
      DIMENSION A(1),B(1)
      IF (IABS(ISN).NE.1) GO TO 10
      CALL SFFT(A,B,N,N,N,ISN,IERR)
      RETURN
   10 IERR=4
      RETURN
      END
