*> \brief \b CSLECT * * =========== DOCUMENTATION =========== * * Online html documentation available at * http://www.netlib.org/lapack/explore-html/ * * Definition: * =========== * * LOGICAL FUNCTION CSLECT( Z ) * * .. Scalar Arguments .. * COMPLEX Z * .. * * *> \par Purpose: * ============= *> *> \verbatim *> *> CSLECT returns .TRUE. if the eigenvalue Z is to be selected, *> otherwise it returns .FALSE. *> It is used by CCHK41 to test if CGEES successfully sorts eigenvalues, *> and by CCHK43 to test if CGEESX successfully sorts eigenvalues. *> *> The common block /SSLCT/ controls how eigenvalues are selected. *> If SELOPT = 0, then CSLECT return .TRUE. when real(Z) is less than *> zero, and .FALSE. otherwise. *> If SELOPT is at least 1, CSLECT returns SELVAL(SELOPT) and adds 1 *> to SELOPT, cycling back to 1 at SELMAX. *> \endverbatim * * Arguments: * ========== * *> \param[in] Z *> \verbatim *> Z is COMPLEX *> The eigenvalue Z. *> \endverbatim * * Authors: * ======== * *> \author Univ. of Tennessee *> \author Univ. of California Berkeley *> \author Univ. of Colorado Denver *> \author NAG Ltd. * *> \ingroup complex_eig * * ===================================================================== LOGICAL FUNCTION CSLECT( Z ) * * -- 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 .. COMPLEX Z * .. * * ===================================================================== * * .. Parameters .. REAL ZERO PARAMETER ( ZERO = 0.0E0 ) * .. * .. Local Scalars .. INTEGER I REAL RMIN, X * .. * .. Scalars in Common .. INTEGER SELDIM, SELOPT * .. * .. Arrays in Common .. LOGICAL SELVAL( 20 ) REAL SELWI( 20 ), SELWR( 20 ) * .. * .. Common blocks .. COMMON / SSLCT / SELOPT, SELDIM, SELVAL, SELWR, SELWI * .. * .. Intrinsic Functions .. INTRINSIC ABS, CMPLX, REAL * .. * .. Executable Statements .. * IF( SELOPT.EQ.0 ) THEN CSLECT = ( REAL( Z ).LT.ZERO ) ELSE RMIN = ABS( Z-CMPLX( SELWR( 1 ), SELWI( 1 ) ) ) CSLECT = SELVAL( 1 ) DO 10 I = 2, SELDIM X = ABS( Z-CMPLX( SELWR( I ), SELWI( I ) ) ) IF( X.LE.RMIN ) THEN RMIN = X CSLECT = SELVAL( I ) END IF 10 CONTINUE END IF RETURN * * End of CSLECT * END