```      SUBROUTINE DRSCL( N, SA, SX, INCX )
*
*  -- LAPACK auxiliary routine (version 3.1) --
*     Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd..
*     November 2006
*
*     .. Scalar Arguments ..
INTEGER            INCX, N
DOUBLE PRECISION   SA
*     ..
*     .. Array Arguments ..
DOUBLE PRECISION   SX( * )
*     ..
*
*  Purpose
*  =======
*
*  DRSCL multiplies an n-element real vector x by the real scalar 1/a.
*  This is done without overflow or underflow as long as
*  the final result x/a does not overflow or underflow.
*
*  Arguments
*  =========
*
*  N       (input) INTEGER
*          The number of components of the vector x.
*
*  SA      (input) DOUBLE PRECISION
*          The scalar a which is used to divide each component of x.
*          SA must be >= 0, or the subroutine will divide by zero.
*
*  SX      (input/output) DOUBLE PRECISION array, dimension
*                         (1+(N-1)*abs(INCX))
*          The n-element vector x.
*
*  INCX    (input) INTEGER
*          The increment between successive values of the vector SX.
*          > 0:  SX(1) = X(1) and SX(1+(i-1)*INCX) = x(i),     1< i<= n
*
* =====================================================================
*
*     .. Parameters ..
DOUBLE PRECISION   ONE, ZERO
PARAMETER          ( ONE = 1.0D+0, ZERO = 0.0D+0 )
*     ..
*     .. Local Scalars ..
LOGICAL            DONE
DOUBLE PRECISION   BIGNUM, CDEN, CDEN1, CNUM, CNUM1, MUL, SMLNUM
*     ..
*     .. External Functions ..
DOUBLE PRECISION   DLAMCH
EXTERNAL           DLAMCH
*     ..
*     .. External Subroutines ..
EXTERNAL           DSCAL
*     ..
*     .. Intrinsic Functions ..
INTRINSIC          ABS
*     ..
*     .. Executable Statements ..
*
*     Quick return if possible
*
IF( N.LE.0 )
\$   RETURN
*
*     Get machine parameters
*
SMLNUM = DLAMCH( 'S' )
BIGNUM = ONE / SMLNUM
CALL DLABAD( SMLNUM, BIGNUM )
*
*     Initialize the denominator to SA and the numerator to 1.
*
CDEN = SA
CNUM = ONE
*
10 CONTINUE
CDEN1 = CDEN*SMLNUM
CNUM1 = CNUM / BIGNUM
IF( ABS( CDEN1 ).GT.ABS( CNUM ) .AND. CNUM.NE.ZERO ) THEN
*
*        Pre-multiply X by SMLNUM if CDEN is large compared to CNUM.
*
MUL = SMLNUM
DONE = .FALSE.
CDEN = CDEN1
ELSE IF( ABS( CNUM1 ).GT.ABS( CDEN ) ) THEN
*
*        Pre-multiply X by BIGNUM if CDEN is small compared to CNUM.
*
MUL = BIGNUM
DONE = .FALSE.
CNUM = CNUM1
ELSE
*
*        Multiply X by CNUM / CDEN and return.
*
MUL = CNUM / CDEN
DONE = .TRUE.
END IF
*
*     Scale the vector X by MUL
*
CALL DSCAL( N, MUL, SX, INCX )
*
IF( .NOT.DONE )
\$   GO TO 10
*
RETURN
*
*     End of DRSCL
*
END

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