      SUBROUTINE ZDROT( N, CX, INCX, CY, INCY, C, S )
*
*     applies a plane rotation, where the cos and sin (c and s) are real
*     and the vectors cx and cy are complex.
*     jack dongarra, linpack, 3/11/78.
*
*     .. Scalar Arguments ..
      INTEGER            INCX, INCY, N
      DOUBLE PRECISION   C, S
*     ..
*     .. Array Arguments ..
      COMPLEX*16         CX( * ), CY( * )
*
* =====================================================================
*     ..
*     .. Local Scalars ..
      INTEGER            I, IX, IY
      COMPLEX*16         CTEMP
*     ..
*     .. Executable Statements ..
*
      IF( N.LE.0 )
     $   RETURN
      IF( INCX.EQ.1 .AND. INCY.EQ.1 )
     $   GO TO 20
*
*        code for unequal increments or equal increments not equal
*          to 1
*
      IX = 1
      IY = 1
      IF( INCX.LT.0 )
     $   IX = ( -N+1 )*INCX + 1
      IF( INCY.LT.0 )
     $   IY = ( -N+1 )*INCY + 1
      DO 10 I = 1, N
         CTEMP = C*CX( IX ) + S*CY( IY )
         CY( IY ) = C*CY( IY ) - S*CX( IX )
         CX( IX ) = CTEMP
         IX = IX + INCX
         IY = IY + INCY
   10 CONTINUE
      RETURN
*
*        code for both increments equal to 1
*
   20 CONTINUE
      DO 30 I = 1, N
         CTEMP = C*CX( I ) + S*CY( I )
         CY( I ) = C*CY( I ) - S*CX( I )
         CX( I ) = CTEMP
   30 CONTINUE
      RETURN
      END
