slctsx.f

Go to the documentation of this file.

*> \brief \b SLCTSX
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*  Definition:
*  ===========
*
*       LOGICAL          FUNCTION SLCTSX( AR, AI, BETA )
*
*       .. Scalar Arguments ..
*       REAL               AI, AR, BETA
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> This function is used to determine what eigenvalues will be
*> selected.  If this is part of the test driver SDRGSX, do not
*> change the code UNLESS you are testing input examples and not
*> using the built-in examples.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] AR
*> \verbatim
*>          AR is REAL
*>          The numerator of the real part of a complex eigenvalue
*>          (AR/BETA) + i*(AI/BETA).
*> \endverbatim
*>
*> \param[in] AI
*> \verbatim
*>          AI is REAL
*>          The numerator of the imaginary part of a complex eigenvalue
*>          (AR/BETA) + i*(AI).
*> \endverbatim
*>
*> \param[in] BETA
*> \verbatim
*>          BETA is REAL
*>          The denominator part of a complex eigenvalue
*>          (AR/BETA) + i*(AI/BETA).
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \ingroup single_eig
*
*  =====================================================================
      LOGICAL          FUNCTION slctsx( AR, AI, BETA )
*
*  -- LAPACK test routine --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*
*     .. Scalar Arguments ..
      REAL               ai, ar, beta
*     ..
*
*  =====================================================================
*
*     .. Scalars in Common ..
      LOGICAL            fs
      INTEGER            i, m, mplusn, n
*     ..
*     .. Common blocks ..
      COMMON             / mn / m, n, mplusn, i, fs
*     ..
*     .. Save statement ..
      SAVE
*     ..
*     .. Executable Statements ..
*
      IF( fs ) THEN
         i = i + 1
         IF( i.LE.m ) THEN
            slctsx = .false.
         ELSE
            slctsx = .true.
         END IF
         IF( i.EQ.mplusn ) THEN
            fs = .false.
            i = 0
         END IF
      ELSE
         i = i + 1
         IF( i.LE.n ) THEN
            slctsx = .true.
         ELSE
            slctsx = .false.
         END IF
         IF( i.EQ.mplusn ) THEN
            fs = .true.
            i = 0
         END IF
      END IF
*
*       IF( AR/BETA.GT.0.0 )THEN
*          SLCTSX = .TRUE.
*       ELSE
*          SLCTSX = .FALSE.
*       END IF
*
      RETURN
*
*     End of SLCTSX
*
      END