zlctes()

logical function zlctes	(	complex*16	z,
		complex*16	d
	)

ZLCTES

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 successfully sorts eigenvalues.

Parameters

[in]	Z	Z is COMPLEX*16 The numerator part of a complex eigenvalue Z/D.
[in]	D	D is COMPLEX*16 The denominator part of a complex eigenvalue Z/D.

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Definition at line 57 of file zlctes.f.

*
*  -- LAPACK test routine --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*
*     .. 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
*

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