| *> \brief \b DLAPY2 |
| * |
| * =========== DOCUMENTATION =========== |
| * |
| * Online html documentation available at |
| * http://www.netlib.org/lapack/explore-html/ |
| * |
| *> \htmlonly |
| *> Download DLAPY2 + dependencies |
| *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dlapy2.f"> |
| *> [TGZ]</a> |
| *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dlapy2.f"> |
| *> [ZIP]</a> |
| *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dlapy2.f"> |
| *> [TXT]</a> |
| *> \endhtmlonly |
| * |
| * Definition: |
| * =========== |
| * |
| * DOUBLE PRECISION FUNCTION DLAPY2( X, Y ) |
| * |
| * .. Scalar Arguments .. |
| * DOUBLE PRECISION X, Y |
| * .. |
| * |
| * |
| *> \par Purpose: |
| * ============= |
| *> |
| *> \verbatim |
| *> |
| *> DLAPY2 returns sqrt(x**2+y**2), taking care not to cause unnecessary |
| *> overflow. |
| *> \endverbatim |
| * |
| * Arguments: |
| * ========== |
| * |
| *> \param[in] X |
| *> \verbatim |
| *> X is DOUBLE PRECISION |
| *> \endverbatim |
| *> |
| *> \param[in] Y |
| *> \verbatim |
| *> Y is DOUBLE PRECISION |
| *> 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 November 2011 |
| * |
| *> \ingroup auxOTHERauxiliary |
| * |
| * ===================================================================== |
| DOUBLE PRECISION FUNCTION DLAPY2( X, Y ) |
| * |
| * -- LAPACK auxiliary routine (version 3.4.0) -- |
| * -- LAPACK is a software package provided by Univ. of Tennessee, -- |
| * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- |
| * November 2011 |
| * |
| * .. Scalar Arguments .. |
| DOUBLE PRECISION X, Y |
| * .. |
| * |
| * ===================================================================== |
| * |
| * .. Parameters .. |
| DOUBLE PRECISION ZERO |
| PARAMETER ( ZERO = 0.0D0 ) |
| DOUBLE PRECISION ONE |
| PARAMETER ( ONE = 1.0D0 ) |
| * .. |
| * .. Local Scalars .. |
| DOUBLE PRECISION 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 |
| DLAPY2 = W |
| ELSE |
| DLAPY2 = W*SQRT( ONE+( Z / W )**2 ) |
| END IF |
| RETURN |
| * |
| * End of DLAPY2 |
| * |
| END |
