slapy2()

real function slapy2	(	real	X,
		real	Y
	)

SLAPY2 returns sqrt(x2+y2).

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Purpose:

 SLAPY2 returns sqrt(x**2+y**2), taking care not to cause unnecessary
 overflow.

Parameters

[in]	X	X is REAL
[in]	Y	Y is REAL X and Y specify the values x and y.

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date

June 2017

Definition at line 65 of file slapy2.f.

*
*  -- 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
*