LAPACK  3.4.1
LAPACK: Linear Algebra PACKage
slctes.f
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00001 *> \brief \b SLCTES
00002 *
00003 *  =========== DOCUMENTATION ===========
00004 *
00005 * Online html documentation available at 
00006 *            http://www.netlib.org/lapack/explore-html/ 
00007 *
00008 *  Definition:
00009 *  ===========
00010 *
00011 *       LOGICAL          FUNCTION SLCTES( ZR, ZI, D )
00012 * 
00013 *       .. Scalar Arguments ..
00014 *       REAL               D, ZI, ZR
00015 *       ..
00016 *  
00017 *
00018 *> \par Purpose:
00019 *  =============
00020 *>
00021 *> \verbatim
00022 *>
00023 *> SLCTES returns .TRUE. if the eigenvalue (ZR/D) + sqrt(-1)*(ZI/D)
00024 *> is to be selected (specifically, in this subroutine, if the real
00025 *> part of the eigenvalue is negative), and otherwise it returns
00026 *> .FALSE..
00027 *>
00028 *> It is used by the test routine SDRGES to test whether the driver
00029 *> routine SGGES succesfully sorts eigenvalues.
00030 *> \endverbatim
00031 *
00032 *  Arguments:
00033 *  ==========
00034 *
00035 *> \param[in] ZR
00036 *> \verbatim
00037 *>          ZR is REAL
00038 *>          The numerator of the real part of a complex eigenvalue
00039 *>          (ZR/D) + i*(ZI/D).
00040 *> \endverbatim
00041 *>
00042 *> \param[in] ZI
00043 *> \verbatim
00044 *>          ZI is REAL
00045 *>          The numerator of the imaginary part of a complex eigenvalue
00046 *>          (ZR/D) + i*(ZI).
00047 *> \endverbatim
00048 *>
00049 *> \param[in] D
00050 *> \verbatim
00051 *>          D is REAL
00052 *>          The denominator part of a complex eigenvalue
00053 *>          (ZR/D) + i*(ZI/D).
00054 *> \endverbatim
00055 *
00056 *  Authors:
00057 *  ========
00058 *
00059 *> \author Univ. of Tennessee 
00060 *> \author Univ. of California Berkeley 
00061 *> \author Univ. of Colorado Denver 
00062 *> \author NAG Ltd. 
00063 *
00064 *> \date November 2011
00065 *
00066 *> \ingroup single_eig
00067 *
00068 *  =====================================================================
00069       LOGICAL          FUNCTION SLCTES( ZR, ZI, D )
00070 *
00071 *  -- LAPACK test routine (version 3.4.0) --
00072 *  -- LAPACK is a software package provided by Univ. of Tennessee,    --
00073 *  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
00074 *     November 2011
00075 *
00076 *     .. Scalar Arguments ..
00077       REAL               D, ZI, ZR
00078 *     ..
00079 *
00080 *  =====================================================================
00081 *
00082 *     .. Parameters ..
00083       REAL               ZERO, ONE
00084       PARAMETER          ( ZERO = 0.0E+0, ONE = 1.0E+0 )
00085 *     ..
00086 *     .. Intrinsic Functions ..
00087       INTRINSIC          SIGN
00088 *     ..
00089 *     .. Executable Statements ..
00090 *
00091       IF( D.EQ.ZERO ) THEN
00092          SLCTES = ( ZR.LT.ZERO )
00093       ELSE
00094          SLCTES = ( SIGN( ONE, ZR ).NE.SIGN( ONE, D ) )
00095       END IF
00096 *
00097       RETURN
00098 *
00099 *     End of SLCTES
00100 *
00101       END
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