1*> \brief \b DLAPY2 returns sqrt(x2+y2).
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 September 2012
60*
61*> \ingroup auxOTHERauxiliary
62*
63*  =====================================================================
64      DOUBLE PRECISION FUNCTION DLAPY2( X, Y )
65*
66*  -- LAPACK auxiliary routine (version 3.4.2) --
67*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
68*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
69*     September 2012
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
105