1 SUBROUTINE DTREVC( SIDE, HOWMNY, SELECT, N, T, LDT, VL, LDVL, VR, 2 $ LDVR, MM, M, WORK, INFO ) 3 DOUBLE PRECISION T( LDT, * ), VL( LDVL, * ), VR( LDVR, * ), 4 $ WORK( * ) 5 DOUBLE PRECISION X( 2, 2 ) 6 CALL DLALN2( .FALSE., 1, 1, SMIN, ONE, T( J, J ), 7 $ ZERO, X, 2, SCALE, XNORM, IERR ) 8 CALL DSCAL( KI, SCALE, WORK( 1+N ), 1 ) 9 DO 90 J = KI - 2, 1, -1 10 IF( J.GT.JNXT ) 11 $ GO TO 90 12 JNXT = J - 1 13 IF( J.GT.1 ) THEN 14 IF( T( J, J-1 ).NE.ZERO ) THEN 15 IF( WORK( J ).GT.BIGNUM / XNORM ) THEN 16 X( 1, 1 ) = X( 1, 1 ) / XNORM 17 END IF 18 END IF 19 CALL DLALN2( .FALSE., 2, 2, SMIN, ONE, 20 $ T( J-1, J-1 ), LDT, ONE, ONE, 21 $ XNORM, IERR ) 22 CALL DAXPY( J-2, -X( 1, 1 ), T( 1, J-1 ), 1, 23 $ WORK( 1+N ), 1 ) 24 CALL DAXPY( J-2, -X( 2, 2 ), T( 1, J ), 1, 25 $ WORK( 1+N2 ), 1 ) 26 END IF 27 90 CONTINUE 28 END 29