LAPACK  3.10.0
LAPACK: Linear Algebra PACKage

◆ slctes()

logical function slctes ( real  ZR,
real  ZI,
real  D 
)

SLCTES

Purpose:
 SLCTES 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 SDRGES to test whether the driver
 routine SGGES successfully sorts eigenvalues.
Parameters
[in]ZR
          ZR is REAL
          The numerator of the real part of a complex eigenvalue
          (ZR/D) + i*(ZI/D).
[in]ZI
          ZI is REAL
          The numerator of the imaginary part of a complex eigenvalue
          (ZR/D) + i*(ZI).
[in]D
          D is REAL
          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 slctes.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  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 *
logical function slctes(ZR, ZI, D)
SLCTES
Definition: slctes.f:68