| *> \brief \b DLAPY3 | |
| * | |
| * =========== DOCUMENTATION =========== | |
| * | |
| * Online html documentation available at | |
| * http://www.netlib.org/lapack/explore-html/ | |
| * | |
| *> \htmlonly | |
| *> Download DLAPY3 + dependencies | |
| *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dlapy3.f"> | |
| *> [TGZ]</a> | |
| *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dlapy3.f"> | |
| *> [ZIP]</a> | |
| *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dlapy3.f"> | |
| *> [TXT]</a> | |
| *> \endhtmlonly | |
| * | |
| * Definition: | |
| * =========== | |
| * | |
| * DOUBLE PRECISION FUNCTION DLAPY3( X, Y, Z ) | |
| * | |
| * .. Scalar Arguments .. | |
| * DOUBLE PRECISION X, Y, Z | |
| * .. | |
| * | |
| * | |
| *> \par Purpose: | |
| * ============= | |
| *> | |
| *> \verbatim | |
| *> | |
| *> DLAPY3 returns sqrt(x**2+y**2+z**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 | |
| *> \endverbatim | |
| *> | |
| *> \param[in] Z | |
| *> \verbatim | |
| *> Z is DOUBLE PRECISION | |
| *> X, Y and Z specify the values x, y and z. | |
| *> \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 DLAPY3( X, Y, Z ) | |
| * | |
| * -- 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, Z | |
| * .. | |
| * | |
| * ===================================================================== | |
| * | |
| * .. Parameters .. | |
| DOUBLE PRECISION ZERO | |
| PARAMETER ( ZERO = 0.0D0 ) | |
| * .. | |
| * .. Local Scalars .. | |
| DOUBLE PRECISION W, XABS, YABS, ZABS | |
| * .. | |
| * .. Intrinsic Functions .. | |
| INTRINSIC ABS, MAX, SQRT | |
| * .. | |
| * .. Executable Statements .. | |
| * | |
| XABS = ABS( X ) | |
| YABS = ABS( Y ) | |
| ZABS = ABS( Z ) | |
| W = MAX( XABS, YABS, ZABS ) | |
| IF( W.EQ.ZERO ) THEN | |
| * W can be zero for max(0,nan,0) | |
| * adding all three entries together will make sure | |
| * NaN will not disappear. | |
| DLAPY3 = XABS + YABS + ZABS | |
| ELSE | |
| DLAPY3 = W*SQRT( ( XABS / W )**2+( YABS / W )**2+ | |
| $ ( ZABS / W )**2 ) | |
| END IF | |
| RETURN | |
| * | |
| * End of DLAPY3 | |
| * | |
| END | |