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LOGICAL FUNCTION CLCTES( Z, D )
* * -- LAPACK test routine (version 3.1) -- * Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. * November 2006 * * .. Scalar Arguments .. COMPLEX D, Z * .. * * Purpose * ======= * * CLCTES returns .TRUE. if the eigenvalue Z/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 CDRGES to test whether the driver * routine CGGES succesfully sorts eigenvalues. * * Arguments * ========= * * Z (input) COMPLEX * The numerator part of a complex eigenvalue Z/D. * * D (input) COMPLEX * The denominator part of a complex eigenvalue Z/D. * * ===================================================================== * * .. Parameters .. * REAL ZERO, ONE PARAMETER ( ZERO = 0.0E+0, ONE = 1.0E+0 ) COMPLEX CZERO PARAMETER ( CZERO = ( 0.0E+0, 0.0E+0 ) ) * .. * .. Local Scalars .. REAL ZMAX * .. * .. Intrinsic Functions .. INTRINSIC ABS, AIMAG, MAX, REAL, SIGN * .. * .. Executable Statements .. * IF( D.EQ.CZERO ) THEN CLCTES = ( REAL( Z ).LT.ZERO ) ELSE IF( REAL( Z ).EQ.ZERO .OR. REAL( D ).EQ.ZERO ) THEN CLCTES = ( SIGN( ONE, AIMAG( Z ) ).NE. $ SIGN( ONE, AIMAG( D ) ) ) ELSE IF( AIMAG( Z ).EQ.ZERO .OR. AIMAG( D ).EQ.ZERO ) THEN CLCTES = ( SIGN( ONE, REAL( Z ) ).NE. $ SIGN( ONE, REAL( D ) ) ) ELSE ZMAX = MAX( ABS( REAL( Z ) ), ABS( AIMAG( Z ) ) ) CLCTES = ( ( REAL( Z ) / ZMAX )*REAL( D )+ $ ( AIMAG( Z ) / ZMAX )*AIMAG( D ).LT.ZERO ) END IF END IF * RETURN * * End of CLCTES * END |