LAPACK 3.11.0
LAPACK: Linear Algebra PACKage
Loading...
Searching...
No Matches
slctes.f
Go to the documentation of this file.
1*> \brief \b SLCTES
2*
3* =========== DOCUMENTATION ===========
4*
5* Online html documentation available at
6* http://www.netlib.org/lapack/explore-html/
7*
8* Definition:
9* ===========
10*
11* LOGICAL FUNCTION SLCTES( ZR, ZI, D )
12*
13* .. Scalar Arguments ..
14* REAL D, ZI, ZR
15* ..
16*
17*
18*> \par Purpose:
19* =============
20*>
21*> \verbatim
22*>
23*> SLCTES returns .TRUE. if the eigenvalue (ZR/D) + sqrt(-1)*(ZI/D)
24*> is to be selected (specifically, in this subroutine, if the real
25*> part of the eigenvalue is negative), and otherwise it returns
26*> .FALSE..
27*>
28*> It is used by the test routine SDRGES to test whether the driver
29*> routine SGGES successfully sorts eigenvalues.
30*> \endverbatim
31*
32* Arguments:
33* ==========
34*
35*> \param[in] ZR
36*> \verbatim
37*> ZR is REAL
38*> The numerator of the real part of a complex eigenvalue
39*> (ZR/D) + i*(ZI/D).
40*> \endverbatim
41*>
42*> \param[in] ZI
43*> \verbatim
44*> ZI is REAL
45*> The numerator of the imaginary part of a complex eigenvalue
46*> (ZR/D) + i*(ZI).
47*> \endverbatim
48*>
49*> \param[in] D
50*> \verbatim
51*> D is REAL
52*> The denominator part of a complex eigenvalue
53*> (ZR/D) + i*(ZI/D).
54*> \endverbatim
55*
56* Authors:
57* ========
58*
59*> \author Univ. of Tennessee
60*> \author Univ. of California Berkeley
61*> \author Univ. of Colorado Denver
62*> \author NAG Ltd.
63*
64*> \ingroup single_eig
65*
66* =====================================================================
67 LOGICAL FUNCTION slctes( ZR, ZI, D )
68*
69* -- LAPACK test routine --
70* -- LAPACK is a software package provided by Univ. of Tennessee, --
71* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
72*
73* .. Scalar Arguments ..
74 REAL d, zi, zr
75* ..
76*
77* =====================================================================
78*
79* .. Parameters ..
80 REAL zero, one
81 parameter( zero = 0.0e+0, one = 1.0e+0 )
82* ..
83* .. Intrinsic Functions ..
84 INTRINSIC sign
85* ..
86* .. Executable Statements ..
87*
88 IF( d.EQ.zero ) THEN
89 slctes = ( zr.LT.zero )
90 ELSE
91 slctes = ( sign( one, zr ).NE.sign( one, d ) )
92 END IF
93*
94 RETURN
95*
96* End of SLCTES
97*
98 END
logical function slctes(ZR, ZI, D)
SLCTES
Definition: slctes.f:68