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*> \brief \b DLCTES
*
* =========== DOCUMENTATION ===========
*
* Online html documentation available at
* http://www.netlib.org/lapack/explore-html/
*
* Definition:
* ===========
*
* LOGICAL FUNCTION DLCTES( ZR, ZI, D )
*
* .. Scalar Arguments ..
* DOUBLE PRECISION D, ZI, ZR
* ..
*
*
*> \par Purpose:
* =============
*>
*> \verbatim
*>
*> DLCTES returns .TRUE. if the eigenvalue (ZR/D) + sqrt(-1)*(ZI/D)
*> is to be selected (specifically, in this subroutine, if the real
*> part of the eigenvalue is negative), and otherwise it returns
*> .FALSE..
*>
*> It is used by the test routine DDRGES to test whether the driver
*> routine DGGES successfully sorts eigenvalues.
*> \endverbatim
*
* Arguments:
* ==========
*
*> \param[in] ZR
*> \verbatim
*> ZR is DOUBLE PRECISION
*> The numerator of the real part of a complex eigenvalue
*> (ZR/D) + i*(ZI/D).
*> \endverbatim
*>
*> \param[in] ZI
*> \verbatim
*> ZI is DOUBLE PRECISION
*> The numerator of the imaginary part of a complex eigenvalue
*> (ZR/D) + i*(ZI).
*> \endverbatim
*>
*> \param[in] D
*> \verbatim
*> D is DOUBLE PRECISION
*> The denominator part of a complex eigenvalue
*> (ZR/D) + i*(ZI/D).
*> \endverbatim
*
* Authors:
* ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date June 2016
*
*> \ingroup double_eig
*
* =====================================================================
LOGICAL FUNCTION DLCTES( ZR, ZI, D )
*
* -- LAPACK test routine (version 3.6.1) --
* -- LAPACK is a software package provided by Univ. of Tennessee, --
* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
* June 2016
*
* .. Scalar Arguments ..
DOUBLE PRECISION D, ZI, ZR
* ..
*
* =====================================================================
*
* .. Parameters ..
DOUBLE PRECISION ZERO, ONE
PARAMETER ( ZERO = 0.0D+0, ONE = 1.0D+0 )
* ..
* .. Intrinsic Functions ..
INTRINSIC SIGN
* ..
* .. Executable Statements ..
*
IF( D.EQ.ZERO ) THEN
DLCTES = ( ZR.LT.ZERO )
ELSE
DLCTES = ( SIGN( ONE, ZR ).NE.SIGN( ONE, D ) )
END IF
*
RETURN
*
* End of DLCTES
*
END
|
