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*> \brief \b DCOMBSSQ adds two scaled sum of squares quantities.
*
* =========== DOCUMENTATION ===========
*
* Online html documentation available at
* http://www.netlib.org/lapack/explore-html/
*
*
* Definition:
* ===========
*
* SUBROUTINE DCOMBSSQ( V1, V2 )
*
* .. Array Arguments ..
* DOUBLE PRECISION V1( 2 ), V2( 2 )
* ..
*
*
*> \par Purpose:
* =============
*>
*> \verbatim
*>
*> DCOMBSSQ adds two scaled sum of squares quantities, V1 := V1 + V2.
*> That is,
*>
*> V1_scale**2 * V1_sumsq := V1_scale**2 * V1_sumsq
*> + V2_scale**2 * V2_sumsq
*> \endverbatim
*
* Arguments:
* ==========
*
*> \param[in,out] V1
*> \verbatim
*> V1 is DOUBLE PRECISION array, dimension (2).
*> The first scaled sum.
*> V1(1) = V1_scale, V1(2) = V1_sumsq.
*> \endverbatim
*>
*> \param[in] V2
*> \verbatim
*> V2 is DOUBLE PRECISION array, dimension (2).
*> The second scaled sum.
*> V2(1) = V2_scale, V2(2) = V2_sumsq.
*> \endverbatim
*
* Authors:
* ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date November 2018
*
*> \ingroup OTHERauxiliary
*
* =====================================================================
SUBROUTINE DCOMBSSQ( V1, V2 )
*
* -- LAPACK auxiliary routine (version 3.7.0) --
* -- LAPACK is a software package provided by Univ. of Tennessee, --
* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
* November 2018
*
* .. Array Arguments ..
DOUBLE PRECISION V1( 2 ), V2( 2 )
* ..
*
* =====================================================================
*
* .. Parameters ..
DOUBLE PRECISION ZERO
PARAMETER ( ZERO = 0.0D+0 )
* ..
* .. Executable Statements ..
*
IF( V1( 1 ).GE.V2( 1 ) ) THEN
IF( V1( 1 ).NE.ZERO ) THEN
V1( 2 ) = V1( 2 ) + ( V2( 1 ) / V1( 1 ) )**2 * V2( 2 )
ELSE
V1( 2 ) = V1( 2 ) + V2( 2 )
END IF
ELSE
V1( 2 ) = V2( 2 ) + ( V1( 1 ) / V2( 1 ) )**2 * V1( 2 )
V1( 1 ) = V2( 1 )
END IF
RETURN
*
* End of DCOMBSSQ
*
END
|
