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*> \brief \b ZSLECT
*
* =========== DOCUMENTATION ===========
*
* Online html documentation available at
* http://www.netlib.org/lapack/explore-html/
*
* Definition:
* ===========
*
* LOGICAL FUNCTION ZSLECT( Z )
*
* .. Scalar Arguments ..
* COMPLEX*16 Z
* ..
*
*
*> \par Purpose:
* =============
*>
*> \verbatim
*>
*> ZSLECT returns .TRUE. if the eigenvalue Z is to be selected,
*> otherwise it returns .FALSE.
*> It is used by ZCHK41 to test if ZGEES successfully sorts eigenvalues,
*> and by ZCHK43 to test if ZGEESX successfully sorts eigenvalues.
*>
*> The common block /SSLCT/ controls how eigenvalues are selected.
*> If SELOPT = 0, then ZSLECT return .TRUE. when real(Z) is less than
*> zero, and .FALSE. otherwise.
*> If SELOPT is at least 1, ZSLECT returns SELVAL(SELOPT) and adds 1
*> to SELOPT, cycling back to 1 at SELMAX.
*> \endverbatim
*
* Arguments:
* ==========
*
*> \param[in] Z
*> \verbatim
*> Z is COMPLEX*16
*> The eigenvalue Z.
*> \endverbatim
*
* Authors:
* ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date June 2016
*
*> \ingroup complex16_eig
*
* =====================================================================
LOGICAL FUNCTION ZSLECT( Z )
*
* -- 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 ..
COMPLEX*16 Z
* ..
*
* =====================================================================
*
* .. Parameters ..
DOUBLE PRECISION ZERO
PARAMETER ( ZERO = 0.0D0 )
* ..
* .. Local Scalars ..
INTEGER I
DOUBLE PRECISION RMIN, X
* ..
* .. Scalars in Common ..
INTEGER SELDIM, SELOPT
* ..
* .. Arrays in Common ..
LOGICAL SELVAL( 20 )
DOUBLE PRECISION SELWI( 20 ), SELWR( 20 )
* ..
* .. Common blocks ..
COMMON / SSLCT / SELOPT, SELDIM, SELVAL, SELWR, SELWI
* ..
* .. Intrinsic Functions ..
INTRINSIC ABS, DBLE, DCMPLX
* ..
* .. Executable Statements ..
*
IF( SELOPT.EQ.0 ) THEN
ZSLECT = ( DBLE( Z ).LT.ZERO )
ELSE
RMIN = ABS( Z-DCMPLX( SELWR( 1 ), SELWI( 1 ) ) )
ZSLECT = SELVAL( 1 )
DO 10 I = 2, SELDIM
X = ABS( Z-DCMPLX( SELWR( I ), SELWI( I ) ) )
IF( X.LE.RMIN ) THEN
RMIN = X
ZSLECT = SELVAL( I )
END IF
10 CONTINUE
END IF
RETURN
*
* End of ZSLECT
*
END
|
