LOGICAL FUNCTION SLCTES( ZR, ZI, D ) * * -- LAPACK test routine (version 3.1) -- * Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. * November 2006 * * .. Scalar Arguments .. REAL D, ZI, ZR * .. * * 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 succesfully sorts eigenvalues. * * Arguments * ========= * * ZR (input) REAL * The numerator of the real part of a complex eigenvalue * (ZR/D) + i*(ZI/D). * * ZI (input) REAL * The numerator of the imaginary part of a complex eigenvalue * (ZR/D) + i*(ZI). * * D (input) REAL * The denominator part of a complex eigenvalue * (ZR/D) + i*(ZI/D). * * ===================================================================== * * .. Parameters .. REAL ZERO, ONE PARAMETER ( ZERO = 0.0E+0, ONE = 1.0E+0 ) * .. * .. Intrinsic Functions .. INTRINSIC SIGN * .. * .. Executable Statements .. * IF( D.EQ.ZERO ) THEN SLCTES = ( ZR.LT.ZERO ) ELSE SLCTES = ( SIGN( ONE, ZR ).NE.SIGN( ONE, D ) ) END IF * RETURN * * End of SLCTES * END