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REAL FUNCTION SLAPY2( X, Y )
* * -- LAPACK auxiliary routine (version 3.2) -- * -- LAPACK is a software package provided by Univ. of Tennessee, -- * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- * November 2006 * * .. Scalar Arguments .. REAL X, Y * .. * * Purpose * ======= * * SLAPY2 returns sqrt(x**2+y**2), taking care not to cause unnecessary * overflow. * * Arguments * ========= * * X (input) REAL * Y (input) REAL * X and Y specify the values x and y. * * ===================================================================== * * .. Parameters .. REAL ZERO PARAMETER ( ZERO = 0.0E0 ) REAL ONE PARAMETER ( ONE = 1.0E0 ) * .. * .. Local Scalars .. REAL 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 SLAPY2 = W ELSE SLAPY2 = W*SQRT( ONE+( Z / W )**2 ) END IF RETURN * * End of SLAPY2 * END |