LAPACK  3.10.1
LAPACK: Linear Algebra PACKage

◆ dlctes()

logical function dlctes ( double precision  ZR,
double precision  ZI,
double precision  D 
)

DLCTES

Purpose:
 DLCTES 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 DDRGES to test whether the driver
 routine DGGES successfully sorts eigenvalues.
Parameters
[in]ZR
          ZR is DOUBLE PRECISION
          The numerator of the real part of a complex eigenvalue
          (ZR/D) + i*(ZI/D).
[in]ZI
          ZI is DOUBLE PRECISION
          The numerator of the imaginary part of a complex eigenvalue
          (ZR/D) + i*(ZI).
[in]D
          D is DOUBLE PRECISION
          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 dlctes.f.

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  DOUBLE PRECISION D, ZI, ZR
75 * ..
76 *
77 * =====================================================================
78 *
79 * .. Parameters ..
80  DOUBLE PRECISION ZERO, ONE
81  parameter( zero = 0.0d+0, one = 1.0d+0 )
82 * ..
83 * .. Intrinsic Functions ..
84  INTRINSIC sign
85 * ..
86 * .. Executable Statements ..
87 *
88  IF( d.EQ.zero ) THEN
89  dlctes = ( zr.LT.zero )
90  ELSE
91  dlctes = ( sign( one, zr ).NE.sign( one, d ) )
92  END IF
93 *
94  RETURN
95 *
96 * End of DLCTES
97 *
logical function dlctes(ZR, ZI, D)
DLCTES
Definition: dlctes.f:68