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LOGICAL FUNCTION ZLCTES( Z, D )
*
* -- LAPACK test routine (version 3.0) --
* Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd.,
* Courant Institute, Argonne National Lab, and Rice University
* June 30, 1999
*
* .. Scalar Arguments ..
COMPLEX*16 D, Z
* ..
*
* Purpose
* =======
*
* ZLCTES returns .TRUE. if the eigenvalue Z/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 ZDRGES to test whether the driver
* routine ZGGES succesfully sorts eigenvalues.
*
* Arguments
* =========
*
* Z (input) COMPLEX*16
* The numerator part of a complex eigenvalue Z/D.
*
* D (input) COMPLEX*16
* The denominator part of a complex eigenvalue Z/D.
*
* =====================================================================
*
* .. Parameters ..
*
DOUBLE PRECISION ZERO, ONE
PARAMETER ( ZERO = 0.0D+0, ONE = 1.0D+0 )
COMPLEX*16 CZERO
PARAMETER ( CZERO = ( 0.0D+0, 0.0D+0 ) )
* ..
* .. Local Scalars ..
DOUBLE PRECISION ZMAX
* ..
* .. Intrinsic Functions ..
INTRINSIC ABS, DBLE, DIMAG, MAX, SIGN
* ..
* .. Executable Statements ..
*
IF( D.EQ.CZERO ) THEN
ZLCTES = ( DBLE( Z ).LT.ZERO )
ELSE
IF( DBLE( Z ).EQ.ZERO .OR. DBLE( D ).EQ.ZERO ) THEN
ZLCTES = ( SIGN( ONE, DIMAG( Z ) ).NE.
$ SIGN( ONE, DIMAG( D ) ) )
ELSE IF( DIMAG( Z ).EQ.ZERO .OR. DIMAG( D ).EQ.ZERO ) THEN
ZLCTES = ( SIGN( ONE, DBLE( Z ) ).NE.
$ SIGN( ONE, DBLE( D ) ) )
ELSE
ZMAX = MAX( ABS( DBLE( Z ) ), ABS( DIMAG( Z ) ) )
ZLCTES = ( ( DBLE( Z ) / ZMAX )*DBLE( D )+
$ ( DIMAG( Z ) / ZMAX )*DIMAG( D ).LT.ZERO )
END IF
END IF
*
RETURN
*
* End of ZLCTES
*
END
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