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    1:       SUBROUTINE ZDRSCL( N, SA, SX, INCX )
    2: *
    3: *  -- LAPACK auxiliary routine (version 3.2) --
    4: *  -- LAPACK is a software package provided by Univ. of Tennessee,    --
    5: *  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
    6: *     November 2006
    7: *
    8: *     .. Scalar Arguments ..
    9:       INTEGER            INCX, N
   10:       DOUBLE PRECISION   SA
   11: *     ..
   12: *     .. Array Arguments ..
   13:       COMPLEX*16         SX( * )
   14: *     ..
   15: *
   16: *  Purpose
   17: *  =======
   18: *
   19: *  ZDRSCL multiplies an n-element complex vector x by the real scalar
   20: *  1/a.  This is done without overflow or underflow as long as
   21: *  the final result x/a does not overflow or underflow.
   22: *
   23: *  Arguments
   24: *  =========
   25: *
   26: *  N       (input) INTEGER
   27: *          The number of components of the vector x.
   28: *
   29: *  SA      (input) DOUBLE PRECISION
   30: *          The scalar a which is used to divide each component of x.
   31: *          SA must be >= 0, or the subroutine will divide by zero.
   32: *
   33: *  SX      (input/output) COMPLEX*16 array, dimension
   34: *                         (1+(N-1)*abs(INCX))
   35: *          The n-element vector x.
   36: *
   37: *  INCX    (input) INTEGER
   38: *          The increment between successive values of the vector SX.
   39: *          > 0:  SX(1) = X(1) and SX(1+(i-1)*INCX) = x(i),     1< i<= n
   40: *
   41: * =====================================================================
   42: *
   43: *     .. Parameters ..
   44:       DOUBLE PRECISION   ZERO, ONE
   45:       PARAMETER          ( ZERO = 0.0D+0, ONE = 1.0D+0 )
   46: *     ..
   47: *     .. Local Scalars ..
   48:       LOGICAL            DONE
   49:       DOUBLE PRECISION   BIGNUM, CDEN, CDEN1, CNUM, CNUM1, MUL, SMLNUM
   50: *     ..
   51: *     .. External Functions ..
   52:       DOUBLE PRECISION   DLAMCH
   53:       EXTERNAL           DLAMCH
   54: *     ..
   55: *     .. External Subroutines ..
   56:       EXTERNAL           DLABAD, ZDSCAL
   57: *     ..
   58: *     .. Intrinsic Functions ..
   59:       INTRINSIC          ABS
   60: *     ..
   61: *     .. Executable Statements ..
   62: *
   63: *     Quick return if possible
   64: *
   65:       IF( N.LE.0 )
   66:      $   RETURN
   67: *
   68: *     Get machine parameters
   69: *
   70:       SMLNUM = DLAMCH( 'S' )
   71:       BIGNUM = ONE / SMLNUM
   72:       CALL DLABAD( SMLNUM, BIGNUM )
   73: *
   74: *     Initialize the denominator to SA and the numerator to 1.
   75: *
   76:       CDEN = SA
   77:       CNUM = ONE
   78: *
   79:    10 CONTINUE
   80:       CDEN1 = CDEN*SMLNUM
   81:       CNUM1 = CNUM / BIGNUM
   82:       IF( ABS( CDEN1 ).GT.ABS( CNUM ) .AND. CNUM.NE.ZERO ) THEN
   83: *
   84: *        Pre-multiply X by SMLNUM if CDEN is large compared to CNUM.
   85: *
   86:          MUL = SMLNUM
   87:          DONE = .FALSE.
   88:          CDEN = CDEN1
   89:       ELSE IF( ABS( CNUM1 ).GT.ABS( CDEN ) ) THEN
   90: *
   91: *        Pre-multiply X by BIGNUM if CDEN is small compared to CNUM.
   92: *
   93:          MUL = BIGNUM
   94:          DONE = .FALSE.
   95:          CNUM = CNUM1
   96:       ELSE
   97: *
   98: *        Multiply X by CNUM / CDEN and return.
   99: *
  100:          MUL = CNUM / CDEN
  101:          DONE = .TRUE.
  102:       END IF
  103: *
  104: *     Scale the vector X by MUL
  105: *
  106:       CALL ZDSCAL( N, MUL, SX, INCX )
  107: *
  108:       IF( .NOT.DONE )
  109:      $   GO TO 10
  110: *
  111:       RETURN
  112: *
  113: *     End of ZDRSCL
  114: *
  115:       END