LAPACK  3.8.0
LAPACK: Linear Algebra PACKage

◆ 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.
Date
June 2016

Definition at line 60 of file zlctes.f.

60 *
61 * -- LAPACK test routine (version 3.7.0) --
62 * -- LAPACK is a software package provided by Univ. of Tennessee, --
63 * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
64 * June 2016
65 *
66 * .. Scalar Arguments ..
67  COMPLEX*16 d, z
68 * ..
69 *
70 * =====================================================================
71 *
72 * .. Parameters ..
73 *
74  DOUBLE PRECISION zero, one
75  parameter( zero = 0.0d+0, one = 1.0d+0 )
76  COMPLEX*16 czero
77  parameter( czero = ( 0.0d+0, 0.0d+0 ) )
78 * ..
79 * .. Local Scalars ..
80  DOUBLE PRECISION zmax
81 * ..
82 * .. Intrinsic Functions ..
83  INTRINSIC abs, dble, dimag, max, sign
84 * ..
85 * .. Executable Statements ..
86 *
87  IF( d.EQ.czero ) THEN
88  zlctes = ( dble( z ).LT.zero )
89  ELSE
90  IF( dble( z ).EQ.zero .OR. dble( d ).EQ.zero ) THEN
91  zlctes = ( sign( one, dimag( z ) ).NE.
92  $ sign( one, dimag( d ) ) )
93  ELSE IF( dimag( z ).EQ.zero .OR. dimag( d ).EQ.zero ) THEN
94  zlctes = ( sign( one, dble( z ) ).NE.
95  $ sign( one, dble( d ) ) )
96  ELSE
97  zmax = max( abs( dble( z ) ), abs( dimag( z ) ) )
98  zlctes = ( ( dble( z ) / zmax )*dble( d )+
99  $ ( dimag( z ) / zmax )*dimag( d ).LT.zero )
100  END IF
101  END IF
102 *
103  RETURN
104 *
105 * End of ZLCTES
106 *
logical function zlctes(Z, D)
ZLCTES
Definition: zlctes.f:60