*> \brief \b SLAPY2 returns sqrt(x2+y2). * * =========== DOCUMENTATION =========== * * Online html documentation available at * http://www.netlib.org/lapack/explore-html/ * *> \htmlonly *> Download SLAPY2 + dependencies *> *> [TGZ] *> *> [ZIP] *> *> [TXT] *> \endhtmlonly * * 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 June 2017 * *> \ingroup OTHERauxiliary * * ===================================================================== REAL FUNCTION SLAPY2( X, Y ) * * -- LAPACK auxiliary routine (version 3.7.1) -- * -- LAPACK is a software package provided by Univ. of Tennessee, -- * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- * June 2017 * * .. 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 LOGICAL X_IS_NAN, Y_IS_NAN * .. * .. External Functions .. LOGICAL SISNAN EXTERNAL SISNAN * .. * .. Intrinsic Functions .. INTRINSIC ABS, MAX, MIN, SQRT * .. * .. Executable Statements .. * * .. * .. Executable Statements .. * X_IS_NAN = SISNAN( X ) Y_IS_NAN = SISNAN( Y ) IF ( X_IS_NAN ) SLAPY2 = X IF ( Y_IS_NAN ) SLAPY2 = Y * IF ( .NOT.( X_IS_NAN.OR.Y_IS_NAN ) ) THEN 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 END IF RETURN * * End of SLAPY2 * END