ZLACRT performs the operation

    (  c  s )( x )  ==> ( x )
    ( -s  c )( y )      ( y )

 where c and s are complex and the vectors x and y are complex.

          N is INTEGER
          The number of elements in the vectors CX and CY.

          CX is COMPLEX*16 array, dimension (N)
          On input, the vector x.
          On output, CX is overwritten with c*x + s*y.

          INCX is INTEGER
          The increment between successive values of CX.  INCX <> 0.

          CY is COMPLEX*16 array, dimension (N)
          On input, the vector y.
          On output, CY is overwritten with -s*x + c*y.

          INCY is INTEGER
          The increment between successive values of CY.  INCY <> 0.

          C is COMPLEX*16

          S is COMPLEX*16
          C and S define the matrix
             [  C   S  ].
             [ -S   C  ]