 LAPACK 3.11.0 LAPACK: Linear Algebra PACKage
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## ◆ clctes()

 logical function clctes ( complex Z, complex D )

CLCTES

Purpose:
``` 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 successfully sorts eigenvalues.```
Parameters
 [in] Z ``` Z is COMPLEX The numerator part of a complex eigenvalue Z/D.``` [in] D ``` D is COMPLEX The denominator part of a complex eigenvalue Z/D.```

Definition at line 57 of file clctes.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 D, Z
65* ..
66*
67* =====================================================================
68*
69* .. Parameters ..
70*
71 REAL ZERO, ONE
72 parameter( zero = 0.0e+0, one = 1.0e+0 )
73 COMPLEX CZERO
74 parameter( czero = ( 0.0e+0, 0.0e+0 ) )
75* ..
76* .. Local Scalars ..
77 REAL ZMAX
78* ..
79* .. Intrinsic Functions ..
80 INTRINSIC abs, aimag, max, real, sign
81* ..
82* .. Executable Statements ..
83*
84 IF( d.EQ.czero ) THEN
85 clctes = ( real( z ).LT.zero )
86 ELSE
87 IF( real( z ).EQ.zero .OR. real( d ).EQ.zero ) THEN
88 clctes = ( sign( one, aimag( z ) ).NE.
89 \$ sign( one, aimag( d ) ) )
90 ELSE IF( aimag( z ).EQ.zero .OR. aimag( d ).EQ.zero ) THEN
91 clctes = ( sign( one, real( z ) ).NE.
92 \$ sign( one, real( d ) ) )
93 ELSE
94 zmax = max( abs( real( z ) ), abs( aimag( z ) ) )
95 clctes = ( ( real( z ) / zmax )*real( d )+
96 \$ ( aimag( z ) / zmax )*aimag( d ).LT.zero )
97 END IF
98 END IF
99*
100 RETURN
101*
102* End of CLCTES
103*
logical function clctes(Z, D)
CLCTES
Definition: clctes.f:58
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