◆ slctes()

logical function slctes	(	real	zr,
		real	zi,
		real	d )

SLCTES

Purpose:

!>
!> SLCTES returns .TRUE. if the eigenvalue (ZR/D) + sqrt(-1)*(ZI/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 SDRGES to test whether the driver
!> routine SGGES successfully sorts eigenvalues.
!>

Parameters

[in]

ZR

!>          ZR is REAL
!>          The numerator of the real part of a complex eigenvalue
!>          (ZR/D) + i*(ZI/D).
!>

[in]

ZI

!>          ZI is REAL
!>          The numerator of the imaginary part of a complex eigenvalue
!>          (ZR/D) + i*(ZI).
!>

[in]

D

!>          D is REAL
!>          The denominator part of a complex eigenvalue
!>          (ZR/D) + i*(ZI/D).
!>

Author: Univ. of Tennessee; Univ. of California Berkeley; Univ. of Colorado Denver; NAG Ltd.

Definition at line 67 of file slctes.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 ..
      REAL               D, ZI, ZR
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      REAL               ZERO, ONE
      parameter( zero = 0.0e+0, one = 1.0e+0 )
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          sign
*     ..
*     .. Executable Statements ..
*
      IF( d.EQ.zero ) THEN
         slctes = ( zr.LT.zero )
      ELSE
         slctes = ( sign( one, zr ).NE.sign( one, d ) )
      END IF
*
      RETURN
*
*     End of SLCTES
*

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