clctes.f

Go to the documentation of this file.

*> \brief \b CLCTES
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at 
*            http://www.netlib.org/lapack/explore-html/ 
*
*  Definition:
*  ===========
*
*       LOGICAL          FUNCTION CLCTES( Z, D )
* 
*       .. Scalar Arguments ..
*       COMPLEX            D, Z
*       ..
*  
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> CLCTES 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 CDRGES to test whether the driver
*> routine CGGES succesfully sorts eigenvalues.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] Z
*> \verbatim
*>          Z is COMPLEX
*>          The numerator part of a complex eigenvalue Z/D.
*> \endverbatim
*>
*> \param[in] D
*> \verbatim
*>          D is COMPLEX
*>          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 complex_eig
*
*  =====================================================================
      LOGICAL          FUNCTION clctes( 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            d, z
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
*
      REAL               zero, one
      parameter( zero = 0.0e+0, one = 1.0e+0 )
      COMPLEX            czero
      parameter( czero = ( 0.0e+0, 0.0e+0 ) )
*     ..
*     .. Local Scalars ..
      REAL               zmax
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          abs, aimag, max, REAL, sign
*     ..
*     .. Executable Statements ..
*
      IF( d.EQ.czero ) THEN
         clctes = ( REAL( z ).LT.zero )
      ELSE
         IF( REAL( z ).EQ.zero .OR. REAL( d ).EQ.zero ) then
            clctes = ( sign( one, aimag( z ) ).NE.
     $               sign( one, aimag( d ) ) )
         ELSE IF( aimag( z ).EQ.zero .OR. aimag( d ).EQ.zero ) THEN
            clctes = ( sign( one, REAL( Z ) ).NE.
     $               sign( one, REAL( D ) ) )
         ELSE
            zmax = max( abs( REAL( Z ) ), abs( aimag( z ) ) )
            clctes = ( ( REAL( Z ) / zmax )*REAL( d )+
     $               ( aimag( z ) / zmax )*aimag( d ).LT.zero )
         END IF
      END IF
*
      return
*
*     End of CLCTES
*
      END