 LAPACK 3.11.0 LAPACK: Linear Algebra PACKage
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## ◆ 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.```

Definition at line 57 of file zlctes.f.

58*
59* -- LAPACK test routine --
60* -- LAPACK is a software package provided by Univ. of Tennessee, --
61* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
62*
63* .. Scalar Arguments ..
64 COMPLEX*16 D, Z
65* ..
66*
67* =====================================================================
68*
69* .. Parameters ..
70*
71 DOUBLE PRECISION ZERO, ONE
72 parameter( zero = 0.0d+0, one = 1.0d+0 )
73 COMPLEX*16 CZERO
74 parameter( czero = ( 0.0d+0, 0.0d+0 ) )
75* ..
76* .. Local Scalars ..
77 DOUBLE PRECISION ZMAX
78* ..
79* .. Intrinsic Functions ..
80 INTRINSIC abs, dble, dimag, max, sign
81* ..
82* .. Executable Statements ..
83*
84 IF( d.EQ.czero ) THEN
85 zlctes = ( dble( z ).LT.zero )
86 ELSE
87 IF( dble( z ).EQ.zero .OR. dble( d ).EQ.zero ) THEN
88 zlctes = ( sign( one, dimag( z ) ).NE.
89 \$ sign( one, dimag( d ) ) )
90 ELSE IF( dimag( z ).EQ.zero .OR. dimag( d ).EQ.zero ) THEN
91 zlctes = ( sign( one, dble( z ) ).NE.
92 \$ sign( one, dble( d ) ) )
93 ELSE
94 zmax = max( abs( dble( z ) ), abs( dimag( z ) ) )
95 zlctes = ( ( dble( z ) / zmax )*dble( d )+
96 \$ ( dimag( z ) / zmax )*dimag( d ).LT.zero )
97 END IF
98 END IF
99*
100 RETURN
101*
102* End of ZLCTES
103*
logical function zlctes(Z, D)
ZLCTES
Definition: zlctes.f:58
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