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    1: *> \brief \b DLAPY2
    2: *
    3: *  =========== DOCUMENTATION ===========
    4: *
    5: * Online html documentation available at 
    6: *            http://www.netlib.org/lapack/explore-html/ 
    7: *
    8: *> \htmlonly
    9: *> Download DLAPY2 + dependencies 
   10: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dlapy2.f"> 
   11: *> [TGZ]</a> 
   12: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dlapy2.f"> 
   13: *> [ZIP]</a> 
   14: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dlapy2.f"> 
   15: *> [TXT]</a>
   16: *> \endhtmlonly 
   17: *
   18: *  Definition:
   19: *  ===========
   20: *
   21: *       DOUBLE PRECISION FUNCTION DLAPY2( X, Y )
   22: * 
   23: *       .. Scalar Arguments ..
   24: *       DOUBLE PRECISION   X, Y
   25: *       ..
   26: *  
   27: *
   28: *> \par Purpose:
   29: *  =============
   30: *>
   31: *> \verbatim
   32: *>
   33: *> DLAPY2 returns sqrt(x**2+y**2), taking care not to cause unnecessary
   34: *> overflow.
   35: *> \endverbatim
   36: *
   37: *  Arguments:
   38: *  ==========
   39: *
   40: *> \param[in] X
   41: *> \verbatim
   42: *>          X is DOUBLE PRECISION
   43: *> \endverbatim
   44: *>
   45: *> \param[in] Y
   46: *> \verbatim
   47: *>          Y is DOUBLE PRECISION
   48: *>          X and Y specify the values x and y.
   49: *> \endverbatim
   50: *
   51: *  Authors:
   52: *  ========
   53: *
   54: *> \author Univ. of Tennessee 
   55: *> \author Univ. of California Berkeley 
   56: *> \author Univ. of Colorado Denver 
   57: *> \author NAG Ltd. 
   58: *
   59: *> \date November 2011
   60: *
   61: *> \ingroup auxOTHERauxiliary
   62: *
   63: *  =====================================================================
   64:       DOUBLE PRECISION FUNCTION DLAPY2( X, Y )
   65: *
   66: *  -- LAPACK auxiliary routine (version 3.4.0) --
   67: *  -- LAPACK is a software package provided by Univ. of Tennessee,    --
   68: *  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
   69: *     November 2011
   70: *
   71: *     .. Scalar Arguments ..
   72:       DOUBLE PRECISION   X, Y
   73: *     ..
   74: *
   75: *  =====================================================================
   76: *
   77: *     .. Parameters ..
   78:       DOUBLE PRECISION   ZERO
   79:       PARAMETER          ( ZERO = 0.0D0 )
   80:       DOUBLE PRECISION   ONE
   81:       PARAMETER          ( ONE = 1.0D0 )
   82: *     ..
   83: *     .. Local Scalars ..
   84:       DOUBLE PRECISION   W, XABS, YABS, Z
   85: *     ..
   86: *     .. Intrinsic Functions ..
   87:       INTRINSIC          ABS, MAX, MIN, SQRT
   88: *     ..
   89: *     .. Executable Statements ..
   90: *
   91:       XABS = ABS( X )
   92:       YABS = ABS( Y )
   93:       W = MAX( XABS, YABS )
   94:       Z = MIN( XABS, YABS )
   95:       IF( Z.EQ.ZERO ) THEN
   96:          DLAPY2 = W
   97:       ELSE
   98:          DLAPY2 = W*SQRT( ONE+( Z / W )**2 )
   99:       END IF
  100:       RETURN
  101: *
  102: *     End of DLAPY2
  103: *
  104:       END