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    1:       DOUBLE PRECISION FUNCTION DLAPY2( X, Y )
    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:       DOUBLE PRECISION   X, Y
   10: *     ..
   11: *
   12: *  Purpose
   13: *  =======
   14: *
   15: *  DLAPY2 returns sqrt(x**2+y**2), taking care not to cause unnecessary
   16: *  overflow.
   17: *
   18: *  Arguments
   19: *  =========
   20: *
   21: *  X       (input) DOUBLE PRECISION
   22: *  Y       (input) DOUBLE PRECISION
   23: *          X and Y specify the values x and y.
   24: *
   25: *  =====================================================================
   26: *
   27: *     .. Parameters ..
   28:       DOUBLE PRECISION   ZERO
   29:       PARAMETER          ( ZERO = 0.0D0 )
   30:       DOUBLE PRECISION   ONE
   31:       PARAMETER          ( ONE = 1.0D0 )
   32: *     ..
   33: *     .. Local Scalars ..
   34:       DOUBLE PRECISION   W, XABS, YABS, Z
   35: *     ..
   36: *     .. Intrinsic Functions ..
   37:       INTRINSIC          ABS, MAX, MIN, SQRT
   38: *     ..
   39: *     .. Executable Statements ..
   40: *
   41:       XABS = ABS( X )
   42:       YABS = ABS( Y )
   43:       W = MAX( XABS, YABS )
   44:       Z = MIN( XABS, YABS )
   45:       IF( Z.EQ.ZERO ) THEN
   46:          DLAPY2 = W
   47:       ELSE
   48:          DLAPY2 = W*SQRT( ONE+( Z / W )**2 )
   49:       END IF
   50:       RETURN
   51: *
   52: *     End of DLAPY2
   53: *
   54:       END