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    1:       SUBROUTINE ZLACRT( N, CX, INCX, CY, INCY, C, S )
    2: *
    3: *  -- LAPACK auxiliary routine (version 3.2) --
    4: *  -- LAPACK is a software package provided by Univ. of Tennessee,    --
    5: *  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
    6: *     November 2006
    7: *
    8: *     .. Scalar Arguments ..
    9:       INTEGER            INCX, INCY, N
   10:       COMPLEX*16         C, S
   11: *     ..
   12: *     .. Array Arguments ..
   13:       COMPLEX*16         CX( * ), CY( * )
   14: *     ..
   15: *
   16: *  Purpose
   17: *  =======
   18: *
   19: *  ZLACRT performs the operation
   20: *
   21: *     (  c  s )( x )  ==> ( x )
   22: *     ( -s  c )( y )      ( y )
   23: *
   24: *  where c and s are complex and the vectors x and y are complex.
   25: *
   26: *  Arguments
   27: *  =========
   28: *
   29: *  N       (input) INTEGER
   30: *          The number of elements in the vectors CX and CY.
   31: *
   32: *  CX      (input/output) COMPLEX*16 array, dimension (N)
   33: *          On input, the vector x.
   34: *          On output, CX is overwritten with c*x + s*y.
   35: *
   36: *  INCX    (input) INTEGER
   37: *          The increment between successive values of CX.  INCX <> 0.
   38: *
   39: *  CY      (input/output) COMPLEX*16 array, dimension (N)
   40: *          On input, the vector y.
   41: *          On output, CY is overwritten with -s*x + c*y.
   42: *
   43: *  INCY    (input) INTEGER
   44: *          The increment between successive values of CY.  INCY <> 0.
   45: *
   46: *  C       (input) COMPLEX*16
   47: *  S       (input) COMPLEX*16
   48: *          C and S define the matrix
   49: *             [  C   S  ].
   50: *             [ -S   C  ]
   51: *
   52: * =====================================================================
   53: *
   54: *     .. Local Scalars ..
   55:       INTEGER            I, IX, IY
   56:       COMPLEX*16         CTEMP
   57: *     ..
   58: *     .. Executable Statements ..
   59: *
   60:       IF( N.LE.0 )
   61:      $   RETURN
   62:       IF( INCX.EQ.1 .AND. INCY.EQ.1 )
   63:      $   GO TO 20
   64: *
   65: *     Code for unequal increments or equal increments not equal to 1
   66: *
   67:       IX = 1
   68:       IY = 1
   69:       IF( INCX.LT.0 )
   70:      $   IX = ( -N+1 )*INCX + 1
   71:       IF( INCY.LT.0 )
   72:      $   IY = ( -N+1 )*INCY + 1
   73:       DO 10 I = 1, N
   74:          CTEMP = C*CX( IX ) + S*CY( IY )
   75:          CY( IY ) = C*CY( IY ) - S*CX( IX )
   76:          CX( IX ) = CTEMP
   77:          IX = IX + INCX
   78:          IY = IY + INCY
   79:    10 CONTINUE
   80:       RETURN
   81: *
   82: *     Code for both increments equal to 1
   83: *
   84:    20 CONTINUE
   85:       DO 30 I = 1, N
   86:          CTEMP = C*CX( I ) + S*CY( I )
   87:          CY( I ) = C*CY( I ) - S*CX( I )
   88:          CX( I ) = CTEMP
   89:    30 CONTINUE
   90:       RETURN
   91:       END