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LOGICAL FUNCTION ZLCTES( Z, D )
* * -- LAPACK test routine (version 3.1) -- * Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. * November 2006 * * .. Scalar Arguments .. COMPLEX*16 D, Z * .. * * Purpose * ======= * * ZLCTES 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 ZDRGES to test whether the driver * routine ZGGES succesfully sorts eigenvalues. * * Arguments * ========= * * Z (input) COMPLEX*16 * The numerator part of a complex eigenvalue Z/D. * * D (input) COMPLEX*16 * The denominator part of a complex eigenvalue Z/D. * * ===================================================================== * * .. Parameters .. * DOUBLE PRECISION ZERO, ONE PARAMETER ( ZERO = 0.0D+0, ONE = 1.0D+0 ) COMPLEX*16 CZERO PARAMETER ( CZERO = ( 0.0D+0, 0.0D+0 ) ) * .. * .. Local Scalars .. DOUBLE PRECISION ZMAX * .. * .. Intrinsic Functions .. INTRINSIC ABS, DBLE, DIMAG, MAX, SIGN * .. * .. Executable Statements .. * IF( D.EQ.CZERO ) THEN ZLCTES = ( DBLE( Z ).LT.ZERO ) ELSE IF( DBLE( Z ).EQ.ZERO .OR. DBLE( D ).EQ.ZERO ) THEN ZLCTES = ( SIGN( ONE, DIMAG( Z ) ).NE. $ SIGN( ONE, DIMAG( D ) ) ) ELSE IF( DIMAG( Z ).EQ.ZERO .OR. DIMAG( D ).EQ.ZERO ) THEN ZLCTES = ( SIGN( ONE, DBLE( Z ) ).NE. $ SIGN( ONE, DBLE( D ) ) ) ELSE ZMAX = MAX( ABS( DBLE( Z ) ), ABS( DIMAG( Z ) ) ) ZLCTES = ( ( DBLE( Z ) / ZMAX )*DBLE( D )+ $ ( DIMAG( Z ) / ZMAX )*DIMAG( D ).LT.ZERO ) END IF END IF * RETURN * * End of ZLCTES * END |