zlctes.f

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*> \brief \b ZLCTES
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at 
*            http://www.netlib.org/lapack/explore-html/ 
*
*  Definition:
*  ===========
*
*       LOGICAL          FUNCTION ZLCTES( Z, D )
* 
*       .. Scalar Arguments ..
*       COMPLEX*16         D, Z
*       ..
*  
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> 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.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] Z
*> \verbatim
*>          Z is COMPLEX*16
*>          The numerator part of a complex eigenvalue Z/D.
*> \endverbatim
*>
*> \param[in] D
*> \verbatim
*>          D is COMPLEX*16
*>          The denominator part of a complex eigenvalue Z/D.
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee 
*> \author Univ. of California Berkeley 
*> \author Univ. of Colorado Denver 
*> \author NAG Ltd. 
*
*> \date November 2011
*
*> \ingroup complex16_eig
*
*  =====================================================================
      LOGICAL          FUNCTION zlctes( Z, D )
*
*  -- LAPACK test routine (version 3.4.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     November 2011
*
*     .. Scalar Arguments ..
      COMPLEX*16         d, z
*     ..
*
*  =====================================================================
*
*     .. 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