slapy2.f

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*> \brief \b SLAPY2 returns sqrt(x2+y2).
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at 
*            http://www.netlib.org/lapack/explore-html/ 
*
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*
*  Definition:
*  ===========
*
*       REAL             FUNCTION SLAPY2( X, Y )
* 
*       .. Scalar Arguments ..
*       REAL               X, Y
*       ..
*  
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> SLAPY2 returns sqrt(x**2+y**2), taking care not to cause unnecessary
*> overflow.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] X
*> \verbatim
*>          X is REAL
*> \endverbatim
*>
*> \param[in] Y
*> \verbatim
*>          Y is REAL
*>          X and Y specify the values x and y.
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee 
*> \author Univ. of California Berkeley 
*> \author Univ. of Colorado Denver 
*> \author NAG Ltd. 
*
*> \date September 2012
*
*> \ingroup auxOTHERauxiliary
*
*  =====================================================================
      REAL             FUNCTION slapy2( X, Y )
*
*  -- LAPACK auxiliary routine (version 3.4.2) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     September 2012
*
*     .. Scalar Arguments ..
      REAL               X, Y
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      REAL               ZERO
      parameter                ( zero = 0.0e0 )
      REAL               ONE
      parameter                ( one = 1.0e0 )
*     ..
*     .. Local Scalars ..
      REAL               W, XABS, YABS, Z
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          abs, max, min, sqrt
*     ..
*     .. Executable Statements ..
*
      xabs = abs( x )
      yabs = abs( y )
      w = max( xabs, yabs )
      z = min( xabs, yabs )
      IF( z.EQ.zero ) THEN
         slapy2 = w
      ELSE
         slapy2 = w*sqrt( one+( z / w )**2 )
      END IF
      RETURN
*
*     End of SLAPY2
*
      END